It has been a big year in personal technology, from the debut and early success of Apple's iPad, to the rise and continuousimprovement of Google's Android smart phone platform, to the continued surge in social services led by Facebook and Twitter.

So I thought I'd take a look at the challenges and opportunities facing some major players in consumer tech in 2011. As with all my columns, this one is focused only on products and services provided directly to consumers, rather than to businesses. Also, as usual, this column isn't meant to offer investment advice or to evaluate the management skills or financial condition of companies. It is a look at the products and competitive positions of the key contenders as they enter the new year.

Apple: Coming off a highly successful 2010, in which it introduced a new category of portablecomputer -- the multitouch tablet -- and sold millions of the product, Apple will have to withstand an onslaught of competitors by wowing consumers again with the second version of the iPad. At the same time, it will have to make a widely expected transition for the iPhone from a single carrier in the U.S., AT&T, to a second, likely Verizon. This could present a new opportunity to reach lots of new customers, but the sleek phone will have to work well on different network technology. At the same time, Apple will be hoping its planned new Macintosh operating system, Lion, can preserve the surprising momentum of the high-priced Mac, which the company is trying to enhance with certain iPad-like features, such as an app store and longer battery life.

In 2011, Apple also is likely to try to address two areas where it has been weak: cloud computing and social networking. Both its MobileMe cloud service and its Ping social network had rough starts, and MobileMe charges $100 a year for services others give away. Apple is so popular, it has a huge opportunity to link users of its family of devices and of iTunes via the cloud and social networks, but it will have to aim higher and execute better. The second area where it likely hopes to improve is in the living room. The new, cheaper Apple TV is selling better than its predecessor but still lacks much Internet content. To break through, Apple will have to strike landmark deals with media companies.

Google: The search giant, also riding high, is now in so many product areas it competes with nearly everyone. In its core search business, it must focus on fending off a surprisingly strong challenge from Microsoft's Bing by giving consumers more attractive, actionable results. Its Android operating system is a big hit, but still isn't as polished or easy to use as the iPhone's software, and even a Google official admitted it is still 'an enthusiast product for early adopters.' One big test will be the forthcoming Honeycomb version of Android, meant for tablets that challenge the iPad.

A separate group at Google will try in 2011 to revolutionize the PC operating-system business and muscle in on Microsoft and Apple. Its new Chrome OS will power notebooks that essentially act as Web browsers, and run programs stored in the cloud, not on a hard disk. They also store all your files in the cloud. We'll learn in 2011 how many consumers are comfortable with that approach.

Google also may take another whack at social networking, where it hasn't made much of a dent after its Buzz service failed to take off. And it will have to rework its overly complex Google TV effort to bring Internet video to the living room.

Microsoft: The software giant still generates strong consumerloyalty with its older products, like Windows and Office and Xbox, all of which have had updates in the past year or two. But it faces big challenges in two hot areas: smart phones and tablets. Its new Windows Phone 7 platform has some nice design features, but also some missing capabilities that need to be addressed. Initial sales seem respectable, but will have to accelerate to get Microsoft back in a game it once led. The company also is a long way from the 300,000 apps for the iPhone or the 100,000 for Android.

In tablets, Microsoft is hinting that a new version of Windows is being designed with a tablet focus to complement its PC focus. That product can't be too late, given the rapid rise of the iPad and the many planned Android and other tablets for 2011. One golden opportunity Microsoft has is to expand the reach of its brilliant Kinect technology for games to other forms of computing. This system can recognize individual users and interpret gestures without the use of a controller device.

Meanwhile, Microsoft hopes to seize on a surge in concern about privacy to help keep its diminishing lead in browsers by building new privacy features, unavailable so far in other browsers, into the 2011 version of Internet Explorer.

RIM: The BlackBerry maker had a good 2010 in some ways, though sales were propped up by two-for-one giveaways, and consumer surveys show enthusiasm fading for the iconic smart phone. It needs a radically new user interface to keep up with iPhone and Android, and a lot more third-party apps. But it can't afford to alienate its fan base. The company has an answer: a new software platform called QNX, but is vague on when that will show up on the BlackBerry. For 2011, RIM's big move will be a new QNX-based tablet, the PlayBook, which looks speedy and attractive in the limited demos RIM has provided. What isn't clear is how much the PlayBook will be aimed at consumers, as company officials have consistently stressed its appeal to businesses.

HP: The technology behemoth's laptops and printers have proved popular with consumers. But it hasn't had any real presence in smart-phones, tablets or consumer cloud services. To solve the problems, in 2010 HP bought innovative but struggling Palm, whose smart-phone operating system, webOS, and phones, the Pre and Pixi, got good reviews but sold poorly and didn't attract many third-party apps. In 2011, HP hopes to use its ample money and talent to revive webOS with new phones and tablets to challenge Apple and Android. A successful Palm re-launch, with the new initiatives from RIM and Microsoft, would be good for consumers by providing more choice and competition. HP also hopes to boost home printing with a new line of printers that can print anything emailed across the Internet and wirelessly print from Apple's hand-held devices.

Facebook and Twitter: The twin leaders in social networking were red-hot in 2010, attracting vast numbers of users. They have huge opportunities for further success, but face challenges. Smaller services, like social-coupon company Groupon, continue to emerge with new social and community ideas consumers like. Apple and Google could be big headaches if they get social right in 2011. Facebook must continue its recent initiative to let members share personal details with more limited groups of friends, and to find ways to make money while offering more privacy, which has been a thorn in its side. Twitter is on a mission to get more than an active minority to post, while convincing people it is a valuable way to keep up with news even if you never post.