I read on another question that the Motorola Defy is a good choice if you want a water resistant phone. I assumed I wouldn't get the phone wet so water resistance was not a factor I considered when I was deciding which phone to buy. As it happened I ended up buying an HTC Desire.
However I do occasionally find it convenient to operate the phone in light rain, or with wet hands. So far no problems apart from a slightly unresponsive touchscreen sometimes, but I'm wondering how much of a risk am I taking here?
Mostly I'm interested in the HTC Desire, but if you have had a similar phone that was damaged by a small amount water then that would be interesting too.
If the water finds its way into the circuitry and causes a short, that could be bad, but I don't think there is any good way to quantify how likely that is to happen to any phone. I have a Moto Droid and get it a little wet all the time and have never had a problem, although I have heard of people bricking their phone under the same circumstances.
If you do actually get it wet and it dies, it may not be bricked. After it dries out it will probably work again. You can aid the process by putting the phone in some rice or just blowing dry warm air on it.
It's also worth noting that many phone manufacturers install moisture detecting stickers inside the phone. On the Droid it can been seen through a little hole under the battery cover that shows red plus signs on a white background. If that gets wet, it'll bleed and that way if you try to return a broken phone and say it just died the tech can see if you got the phone wet, and even if that's not why it died, it'll void your warranty.
I have a HTC Nexus One and carelessly ended up with it being immersed in three inches of river water in the bottom of a plastic bag for over an hour. I assumed that it would be write-off but dried it out anyway in the sunshine on the dashboard or the car and held it in the warm summer breeze for an hour on the journey home. I put the battery and cards back in and after a short period of irregular displays it worked perfectly. I was astonished!
Most phones work pretty fine with a little amount of water, but it also depends on your luck. My first Android volume buttons stopped working after I played Basketball with it in my pocket and sweat screwed it up. Under warranty got it replaced.