I know, it sounds like something that you'd catch if you hadn't taken precautions! However, as a verb, it appears to mean collecting data (particularly data regarding someone's taste in music) in order to refine service delivery and/or for social networking purposes. The (rather convoluted) wiki definition goes thus:
To publish one's music-listening habits via software, as counted events when songs or albums are played, to selected internet services in order to track them over time, out of curiosity and/or to make them visible to others.It seems that it all stems from Last.fm, an Internet radio site that records the details of its listeners' musical tastes to better provide content to its audience.
So, there you have it: when we give up this information willingly it's called freedom (or, scrobbling ;)), if it's taken by stealth, it's called invasion of privacy.
Just trying to learn you all something!