Search and online advertising giant Google recently filed a patent for an in-game advertising system:
The patent's abstract description reads, "Information about a person's interests and gaming behavior may be determined by monitoring their online gaming activities (and perhaps making inferences from such activities). Such information may be used to improve ad targeting."
The folks at Shacknews have fished out a few choice bits from the patent itself, including a claim that says a user's dialogue and gameplay style "may be used to characterize the user." A situation where a user might be asked to listen to a new Coldplay album in a "Sims type game" is also described. In that case, the user's responses to that ad and others could be tracked.