You've probably heard about the Mars Pathfinder probe. Once it lands on the Red Planet, Pathfinder will release the Sojourner Rover, a little laboratory on wheels. Sojourner will cruise about the Martian surface performing experments. It turns out that Sojourner and Pathfinder will communicate using two standard, off-the-shelf 9600 baud radio modems.
According to Jet Propulsion Laboratory program manager Donna Shirley, the modem manufacturer warned JPL that sending the modem to Mars would void the warrantee.
(This came from amsat-bb, an email list for amateur radio satellite enthusiasts).