Do you hear that ticking noise? It's your iPhone's warranty preparing to go "boom." If you purchased your iPhone on the original US release date -- June 29, 2007 -- your warranty will expire in three days (as of this writing) on June 29th, 2008.
Of course, you can extend coverage by purchasing AppleCare for the iPhone at $69.95US (or toss in an additional $129 for iPhone 3G). Otherwise, get yourself to an Apple Store Genius Bar ASAP!
If the iPhone is anything like most cars I've owned, everything will go wrong the very day after the warranty expires. I'm just saying.