iOS 4.3.5 has just been released by Apple through iTunes, for now I don't know what this version of iOS brings, but I recommend you NOT to UPDATE! This new version of iOS comes just a week and a half after the release of iOS 4.3.4 which blocks the possibility of jailbreaking using the jailbreakme.com 3.0 solution. The only novelty brought by this version of iOS consists in solving some security problems regarding the validation of certificates, so you have no reason to update for now.
UPDATED: You can download iOS 4.3.5 from here.
