I won't even put my phone down on the same counter I'm pouring my coffee on. And I wrote the article that Belodion linked to. I've seen too many phones that were cleaned properly (and quickly) after they got wet still fail long before they would normally need to be replaced.
My rule of thumb is to treat my phone as if it were soluble in water. I wear it in a holster on my belt, but if I have to go somewhere in the rain, the phone comes out of the holster and into an inside pocket. If it's pouring (we sometimes get inches-per-hour downpours here in the summer), the phone goes into a zipped plastic bag, or I switch the SIM to my cheap dumb phone (which would cost me about $10 to replace from Craig's List - but it's a phone and. I don't like being out and about without one).