5-10 minutes under water. Does my iPhone 3G have any chance of recovery?

It had a better chance until you turned on it on. How much time passed between it being in the tub and you turning it on?

If an electronic gets wet it will generally shut off right away when the circuits detect the water. The best thing is to then put it in a dry cool place for at least a week to dry out. You can also put it in a plastic zip lock bag with some uncooked rice to draw out the moisture, change the rice every other day.

The damage comes from turning it back on too soon, if there is still moisture in there you can short out the circuits and at that point it is done. You can try to let it sit a little longer and see if it comes back to life.

I've seen a cell phone go through the washing machine and after sitting for a week it worked perfectly.

Do an ebay search for "water damaged iphone" and check your options on repair or just selling it.

William.

If it is dead
http://arstechnica.com/apple/news/2009/05/apple-changes-water-damaged-iphone-rep lacement-policy.ars
I'm not sure if this is fake, or a rumor. But it beats paying full price