An article on SDTimes ("Delphi IDE retooled for Visual Studio 2010") and a YouTube video (see below) shed some light on the next version of Delphi Prism for Visual Studio 2010.

In the article we learn that Delphi Prism 2011 for Visual Studio 2010 is set for release on May 15, 2010 (am I the only one who finds this product numbering strategy a nonsense?). The company "promises cleaner connectivity to InterBase and Blackfish SQL databases, as well as the ability to create DataSnap clients in .NET that connect to Delphi DataSnap servers for multi-tier applications. New features include code obfuscation, parallel extensions and the ability to convert C# code into the Prism language." 

You'll find an actual demo of some of this features, given by David I, in the following YouTube video, which is part of "VSIP Partners CAN DO! | Embarcadero Technologies Delphi Prism":

Looks quite nice. What's negative is that it seems Silverlight 4, won't be supported immediately, but only later in the release cycle (which is a quarterly cycle for Prism, as most RemObjects tools).