At 4:49pm Tuesday evening, the account @Bill_Clinton12 sent its relatively tame first tweet: "There's no question the #MittRomney has had a sterling business career." A link to Romney's campaign page was tacked on at the end of this and certain subsequent tweets. (The link takes you to a page with choice quotes of Clinton saying favorable things about Romney in interviews with various political outlets.)
The parody Clinton account has only 11 tweets, at this writing—the later ones increasingly hokey, beginning "Ruh roh!" and "Oopsies!" and "I'm back, baby!!"