My iPhone 3G took a dive into the toilet (not a very smart decision), luckily I had already flushed the toilet. I rescued the phone (using gloves) and immediately put it in a bag with rice (as advised) for two weeks. it came back on but just to show me the white apple logo and that was it. I went ahead and order the new iPhone 4G and forgot about the iPhone 3G. As I was doing my fall cleanup I ran accross the drowned iPhone 3G I thought I would give it a try, but same story...the white apple logo when I plugged into the charger. Since I already had a replacement phone I thought I would give it a shot at repairing it, so I followed the guides at the ifixit.com website...
I took it apart following the 3G iPhone repair guide and soaked the logic board in alcohol. I ordered the battery which arrived three days later (very fast shipping), as soon as it arrived I put it in following the instructions and in less than 15 minutes, the phone started working better than before it went swimming because now the battery was new.
It was a $20 dollar and total of 1 hour investment of time for a dead 3G iphone, it is worth giving it a try and hopefully bring it back to life. Now the phone is worth more than my investment and I learned a lot following the guide. Not bad for my first attempt to take apart and put togheter an iPhone.