Just a FYI. Apple have released iTunes 9.1 (in prep for the iPad launch)
Reports are all over that it breaks the blackra1n Jailbreak process so be aware that it may not be a great idea to update right away.
From:http://thebigboss.org/2010/03/30/windows-users-avoid-itunes-91/
It appears that Apple has released iTunes 9.1. If you are on windows, I would avoid using this. It seems to have problems with blackra1n because blackra1n uses a specific DLL that has changed.
Reports are all over that it breaks the blackra1n Jailbreak process so be aware that it may not be a great idea to update right away.