What Works:
iPhones & iTouches & iPads
(works as is but entering the URL into the browser of the ooTunes app will allow skipping tracks)
Most Blackberries
Droids
(with the "Just Playlists" or "Droid Live" apps available free on Android Market)

What Doesn't Work:
Most Droids (without app), Palm, and some Blackberries

Unknown:
Squeezeboxes