Professor Mark A. Lemley is quoted in the ABA Journal in a story about users' objections to changes Facebook proposed to its terms of service:

“Thirty years ago, no one would have said these unilateral agree­ments were enforceable,” says Stanford Law School professor Mark A. Lem­ley, director of the school’s Program in Law, Science and Technology. But traditional contract law has changed, he says, and courts are enforcing click-through agreements on software and other kinds of unilateral agreements.

While Lemley says reaction to the Facebook changes was out of proportion, it suggests the level of expectation users have about control over what they put online.