Sitecore CMS 6.0.0 Update rev.080820 is released: http://sdn5.sitecore.net/SDN5/Resources/Sitecore%206/Sitecore%206.0.aspx.
The most notable fix is .NET 3.5 Service Pack 1 compatibility.
Disclaimer The opinions expressed herein are my own personal opinions and do not represent my employer's view in anyway.