Napster for all kinds of software
Wrapster, which modifies the PC Napster into a tool to transfer/trade any type of file with the ease of Napster.
This is something we knew was coming, and even hinted at by Napster's creator. (though Wrapster is a 3rd party app).
Mac users should be aware of the Macster port for MP3's, and there is no Mac version of Wrapster (yet). Good, bad, who knows... it certainly makes for an interesting drama.