We’ve all be waiting a long time for that, but with the new Visual studio 2010 sp1 (in beta), we can create and run Sharepoint 2010 unit tests from Visual studio 2010.(new support for the .Net Framework 3.5).
The following very short videos on Channel 9 illustrates how it works (or download it and run it in full screen).
Here is the English version (switch to full screen mode):
…and here is the French version (switch to full screen mode)
Best whishes for 2011!