Why chirpy v2 (last version) does'nt work on vs2010 ASP.NET 4 but work on vs2010 ASP.NET 3.5 or earlier?
It's site: http://chirpy.codeplex.com
Try version 2.0.4, which wasn't available when you asked this question. If you go to the Chirpy codeplex page and click download, you get v2.0.1, which is marked as the recommended release (not sure why).