What about using a remote receiver, located in the vanity or linen closet, speakers in the shower stall, and a remote IR bud (wired back to the receiver) in the shower stall? (there are water proof remotes for things like hot tubs)
That way, you got the sound, and dropping the remote control would be no worse than dropping the soap! (kind of depends on your situation, I guess!)
In all seriousness, If I were planning to put fancy radio output in the shower stall, I'd plan for things like replacing/upgrading the receiver, and also include in the plans, having speakers and a means of control outside the shower stall (by the sinks, etc), as shaving/doing hair/makeup can take up more time in the bathroom than a shower. Add another IR bud or two, and a couple more speakers and you're covered. What if you wanted to add a CD or IPOD player for example. A external receiver could make this much easier.
My 2c worth, but then again, I find a Sony AM/FM shower radio just fine for the time I'm in the bath.. I for one usually don't change the station on the radio once I'm in the shower, as my showers don't last that long, and any spare time is spent pondering what that green stuff between my toes really is.. I'm bald, so "doing my hair" isn't a problem, and I don't wear makeup!