It already lets you share photos, contacts, social network links, PayPal money transfers, and (on iPhone 4's) calendar events — and now Bump shares music as well. The free iPhone app, which literally allows two iPhones running the app to "bump" together to exchange data, adds music sharing to version 2.2.
Well, "music sharing" after a fashion. You're not actually sharing physical music files, 'cuz that would be getting into Napster/Limewire territory; instead, you're sharing a music recommendation. The recipient of your audio Bump can stream the tune from YouTube, hear a preview on Itunes, or buy the entire track from same.
(Mind you, if you recommend an Ugly Kid Joe track to a fellow iPhoner, you're literally…er…"Bumping Uglies.")