How will Microsoft address the ARM-based tablet space?

Bloomberg is reporting that Microsoft will announce at the upcoming Consumer Electronics Show (CES) a version of Windows that will work on ARM.

If I were a betting woman, I'd bet against my esteemed colleagues/competitors on this one. Instead, I would wager that Microsoft will announce a new version of Windows Embedded Compact that will work on ARM-based tablets.

I'm thinking this could happen for a few reasons:

* Windows Embedded Compact/Windows CE already runs on ARM

* Microsoft is close to releasing to manufacturing its Embedded Compact 7 version of that platform (It was supposed to RTM this year, but was delayed until Q1 2011.)

* Microsoft has been working to port Windows to ARM (as far back as with Vista, under project LongARM), but either couldn't or wouldn't release that port

Steven Guggenheimer, Microsoft's OEM chief -- who, in the past, has been a champion of Windows Embedded Compact tablets and slates -- is slated to address Wall Street analysts on January 6, 2011, the day after Microsoft CEO Steve Ballmer's CES kick-off speech. Guggenheimer might be the guy to talk about Microsoft's evolving Windows slate strategy, but I'm thinking, given his past speeches, he's going to talk up Embedded Compact tablets.

Microsoft execs have been unclear, perhaps intentionally, perhaps not -- about exactly what counts as a "Windows" tablet/slate. When Ballmer talked about Microsoft's longer-range tablet/slate plans earlier this year, he showed a slide with 20+ Microsoft OEM tablet/slate partners. Many of those partners are in the business of providing Embedded Compact/CE mobile devices.

My understanding is Windows 7 slates and Windows Embedded Compact 7 slates won't be able to run the same apps. Because both platforms will support Silverlight, there could be some cross-platform synergies. And who knows -- maybe Microsoft will port the Metro/Media Center UI to Windows Compact Embedded. That would be the next-best thing to bringing the full Windows Phone OS to tablets or slates (something the Softies have said they currently are not planning to do).

But remember: Just because something is called a "Windows" tablet, even by Microsoft, may not necessarily mean it is running the same Windows OS that runs on PCs.

CES is just a couple of weeks away. It'll be interesting to see what the Softies have to say about slates, regardless of which OS they are running.

Update: The Wall Street Journal also is saying a new version of Windows for tablets is coming but is a couple years away. That sounds, as Business Insider's Matt Rosoff noted, like Windows 8. (Or maybe it will be more like a Windows 8 "Lite"?) If it is Windows 8, maybe the long journey involving porting Windows to ARM will finally culminate in a shipping product (albeit one that is timed to arrive in late 2012/early 2013).

In any event, Microsoft is not commenting on any reports about its CES plans....