One of the most common questions I hear when talking about the Database Professional edition is "does it support anything other than SQL Server?" And my standard response was always "not at this time" -- which was not a real 'no' but more of a 'not yet'.
Well, I'm very glad to report that we've made our first announcements around multi-platform support. Working in conjunction with IBM, DBPro will be gaining support for DB2! Read all about it here: DataDude Goes Multi-Platform. Want to see for yourself? Learn how to download the preview from here: VSTS 2008 Database Edition GDR June CTP.
So, are SQL and DB2 the only supported platforms? "Yes, at this time." :) . Actually, read that 2nd linked posting carefully, and you'll read that "there are others that are working on providers for other database management systems."