I've been having the following problems since I've had my phone, not just since the 2.2 update.
Every time I enable wifi my service sucks. Web pages take forever to load, if at all. Applications like facebook and twitter are rendered useless. Every time I try to post, check updates, etc I get error messages.
And no, it's not my connection. I play online games with my 360 and ps3 wirelessly without issues.