Been busy upgrading to SP2 on a couple of sites, and doing a lot of test of new stuff while my students are doing labs. No issues as of yet with sp2. However on codeplex I found some interesting stuff:

SPMessaging – Twitter variant for your sharepoint:
http://spmessaging.codeplex.com/

Windows Live Authentication – Actually works and is quite simple to implement
http://spwla.codeplex.com/

Powershell console in sharepoint – A perfect complement to the Powershell components of iLoveSharepoint
http://sppowershellconsole.codeplex.com/