Now that the RC (Release Candidate) is out in public Exchange 2010 Release Candidate info page I can only say that it’s starting to look really good. Features that before where only talked about now is in this build and also work pretty good.
From now on to RTM version, it is mostly bug checking and performance tuning.
For you that seek for the 32bit version of Exchange 2010, the answer is, there will not be any 32bit version of any kind, no demo version, no admin tools no nothing.
Sign up for download here http://technet.microsoft.com/en-us/evalcenter/dd185495.aspx
Here is the Exchange team info msexchangeteam blog