Quoted from the Kuju website:
Rail Simulator took to the Rails publicly for the first time last week at the annual European Games Convention at Leipzig and announced a working partnership with Deutsche Bahn. The first playable version of the game was exhibited on the EA Games and Microsoft Games for Windows stands which attracted 180k consumers, and was presented in the Business Lounge to worldwide press!
See also the Rail Simulator website.
From reading the full article in the first link, it would appear that Microsoft has some involvement. Of course, this may just be a poorly worded news release or a poor translation. Stay tuned!
Check out the video at the second link. It reminds me of Trainz, except the landscape grid appears much finer and the moving people at the station are awesome.