Steve Ballmer at CES last year

Microsoft CEO Steve Ballmer will be in Las Vegas this week for his second Consumer Electronics Show keynote since assuming the high-profile speaking slot from Bill Gates. It's a pivotal moment for the company, in a variety of ways. Windows 7 launched successfully, and the Xbox 360 is holding its own, but Microsoft's mobile business is struggling -- contributing to dire predictions about its consumer initiatives.

With that as backdrop, Ballmer's speech is shaping as an important barometer of the company's business for the next year and beyond. Here are some of the areas we'll be keeping an eye on.

Windows Mobile: Here's where the keynote will win or lose in the eyes of many in the CES crowd, given the increasingly central role of mobile technologies in the broader industry. Whether or not Ballmer is ready to preview Windows Mobile 7, his speech will be watched closely by application developers, mobile operators and others for signs of revival or continued decline in Microsoft's mobile business. Given the momentum for iPhone and Android, it's shaping up as a make-or-break moment for Microsoft.

Tablets: With speculation rampant about Apple's plans for a new tablet-style computer, it's worth remembering that Microsoft made a big push into this market a long time ago, in the early part of the last decade, ultimately falling well short of its own aspirations. Even if the Redmond company isn't prepared to unveil its Courier dual-screen tablet, or related projects, it will be interesting to see if Microsoft can trot out more than a few token Tablet PC convertibles to demonstrate its continued interest in this "niche."

Windows 7 PCs: This year's CES gives Microsoft and computer makers an opportunity to showcase new hardware running the new operating system. Lenovo has already tipped its hand, unveiling products including the ThinkPad Edge, as reported by Engadget over the weekend. HP's CES lineup also leaked in advance, but generated a big yawn from tech bloggers. In particular, we'll be watching to see how many hardware makers are taking advantage of new Windows 7 features, such as touch-screen support.

Project Natal: After unveiling this motion-sensing Xbox 360 control system at last year's E3 video-game convention, the company has been mostly mum on minor details such as, oh, when the thing will actually be available. Particularly if Natal is launching this year, as widely assumed, CES would be an obvious place for Microsoft to get more specific about the timing and, just as important, reveal and demonstrate some of the games that will work with the technology. At the very least, expect the company to show Natal on stage.

Automotive: Microsoft has made headway in the U.S. auto market by providing the underlying technology for Sync, the hands-free digital "infotainment" system from Ford. The continued evolution of that system will be a key topic at CES this year, with Ford CEO Alan Mulally taking the stage the morning after Ballmer does.But Microsoft's automotive unit will also be focusing on its partnerships with other automakers, including Kia, which is expected to unveil details of its new "UVO" in-car technology at the show.

Xbox Live: Microsoft's online gaming system been evolving nicely as an entertainment and communication platform, with the addition of such services as Netflix, Last.fm, Twitter and Facebook. Look for that trend to continue this year, and it wouldn't be a surprise to hear Ballmer or Microsoft Entertainment & Devices chief Robbie Bach announce new Xbox Live content partnerships at the show. And as we noted last week, isn't it about time to actually bring Xbox Live to Windows Mobile, and not just talk about its plans?

Other stuff to watch: Mediaroom, Microsoft's IPTV technology, is expected to have a presence at the show. Meanwhile, the company has been adjusting its Zune music initiative to focus more on putting the Zune service on a variety of devices, and there could be more signs of that trend at CES this week.

And finally, if I were putting a bet on a long-shot announcement from Microsoft, it would be an external Blu-ray drive for Xbox 360 -- despite the company's previous insistence that it has no such plans. Yeah, it probably won't happen, but that's why it's an interesting long shot.