I am writing some programs for use in PDA's in potentially wet environments (fish traps). I wanted to make sure that the data on the SD cards would survive immersion, so I took a card and left it in a glass of water for a day: No harm done.
That test may not have been very definitive. Tap water in a glass is not a terribly harmful environment. Somebody on this site told me about leaving a chip in a glass of orange juice for an hour (citric acid and sugars, more conductive than tap water). Now I'm thinking of more severe tests:
Flat coke (pH 1.8, so it's more acidic than stomach acid)
Washing machine: Front loader, so there would be agitation, soap, and dirty socks.
Dish Washer: Heat, pressure, soap, spaghetti sauce.