Just saw this in the video Bla1ze posted for the CES Wrap-up from RIM.
If you watch the video, there is a top-swipe for options done and it bring up MS Word-related options, not Remote Desktop-related options, so this isn't a Remote Desktop app running.
I was able to grab another screenshot that shows Microsoft Word, Microsoft Excel, and Microsoft Powerpoint running at the same time in the tabs when a top-swipe is done.
There is a also a Log Off button (so this could be a Remote Desktop App), and another button that I cannot make out.
Go to 45 sec on the same video, and freeze - Citrix remote app. It IS Word. Although I would love to see Docs to Go get this level of sophistication. Oh well, waiting for promised Smartoffice from Picsel.
I believe it's Citrix as well, though I think that this may also be the future for Playbook and ultimately BBX/10 Phones, the ability to use very powerful applications through "the cloud" or remotely, where valuable resources won't have to be utilized on your device to run the program.
Besides Docs to Go can't use trademarked Microsoft Titles unless they recently reached a licensing agreement, but that's doubtful.