Did you buy an iPhone 4 with AppleCare around launch day back in 2010? Bad news, your warranty's about to expire. Good news, Apple is pretty generous with replacing defective phones. Head over to Cult of Mac for a list of common replacement-triggering maladies.
Yes there's almost definitely going to be a new iPhone out this fall, but there are still plenty of reasons for you to get it replaced if possible. At the very least, it's worth getting that 90-day warranty extension so that you're fully covered up until launch day. After all, you already paid for the warranty at this point; why let it go to waste? [Cult of Mac]