I have a 3G bought in July/Aug '08 and just started having issues with the iPod on my phone. I've been using brand X head phones and an aux input for the car. Lately, the sound has only played through the car's right speakers and my headphones right side. HELP! I baby my phone no more/less than everyone here and nothing has happened lately. I can't figure out what the issue is 
I just tried playing apps and I have the same issue. I also just plugged my headphones into my MacBook and they work great! By playing with my headphone or aux wires while connected to my phone sound will temporarily come out of both sides BUT the volume is extremely LOW (even with the volume turned all the way up).
I'm approx 75% positive I had this problem prior to 3.1
I just tried playing apps and I have the same issue. I also just plugged my headphones into my MacBook and they work great! By playing with my headphone or aux wires while connected to my phone sound will temporarily come out of both sides BUT the volume is extremely LOW (even with the volume turned all the way up).
I'm approx 75% positive I had this problem prior to 3.1