Thanks for the suggestions, but perhaps I wasn't clear enough. There are already speakers built into the ceilings of the living room, kitchen, master bedroom, and master bath. Each room has an individual volume control knob, and each set of speakers has wiring running down to that second floor and out of the wall. There's nothing to connect to those speakers in the individual rooms (aside from volume), it all has to come from that second floor. I figured that if I could find some way to get amplified wireless audio to that second floor from the first, I could set her up with the iPod Touch and she'd have a pretty cool system (and a nice iPod too).

Most of the wireless speaker options I've seen don't output much more than 25W RMS. Is that enough for 8 in-wall speakers? I assumed no... The only ones I've found are intended to power surround speakers.