iPhone 3G Microphone Problem?

Well, I have had my iPhone for about a month now, and this is the second time it has broken on me.
The first time, the screen went white. Every time i started, restarted, or reset the phone the screen would come up white and stay that way. I brought it to the apple store, and they just gave me a new one.
This time, my microphone doesn't work. I can here everyone but no one can here me. I haven't tried it on speaker phone to see if that works. But, I think I'll just take it to the genius bar and let them give me a new one.
I have hear about a few problems with these phone, but you have to give it to Apple, atleast for thier customer service.

I have to say this in interesting to read. I never encounter this problem until 12/9, Tuesday. Now I had my iPhone plugged into a cassette adapter in my car. I unplugged it and called someone and they could not hear me. I plugged and unplugged the adapter hoping to fix it, no dice. I tried resetting twice, no dice. I tried plugging and unplugging some PC speaker, No Dice. I then tried the headset that came with the iPhone, No Dice. I tried resetting again, No Dice. I finally plugged unplugged the PC speakers about 3 time in a row and the mic started working. Any way that was my experience with it on 12/9. No problems prior or after.

I had the same problem with a brand new 2.0.2 iPhone! Interesting thing was, if I plugged in the hands free, there will be the same distortion on the other side of the line, yes, with the handsfree mic. Guess what? Fixed it by doing a restore to 2.2. The irony.

I bought a 3G in 12/2008 and have had no problems. Today suddenly, with no dropping and no use of attached devices, no one can understand me (sometimes no sounds, sometimes very garbled/noisy) when I speak using the phone to my ear. I hear them fine. If I switch to speakerphone, everything is fine. Restarting and resetting had no effect. Software has been at 2.2.1 since it came out. When I switch back from speakerphone to regular mode, they can hear me a little better, but still garbled (and this appears to be consistent). Ocarina was downloaded and it WORKS fine. What does that mean??? A software issue? If this persists tomorrow, can I easily exchange at the Apple Store tomorrow even if I didn't buy the Apple Care policy?

I tried using the included earbuds. It's still the same behavior. I can hear the caller, but they either don't hear me at all, or they hear static/garbled noises. If I change to speakerphone, we can hear each other fine. I'm baffled.
--Scott

I went to the Apple Store in Manhattan Beach. They got me help in 5 minutes. They did a software restore, verified that the problem was still there, and gave me a new phone. Wow.