RENAISSANCE REDUX: Plato Learning, owned by private equity firms Thoma Bravo and HarbourVest, just won't give up: on Monday, it offered an unsolicited bid of $16.90 a share ($496 million) for Renaissance Learning. Renaissance's board had previously snubbed Plato and accepted a $16.60/share bid from private equity firm, Permira. A vote is slated for next week. This is as mysterious as takeovers get, as the NYTimes details. Cofounders Terrance and Judith Paul own 69% of Renaissance and have said they aren't keen to sell to Plato; Renaissance is incorporated in Wisconsin (not Delaware) and so they're not required to accept the highest bid. They've also agreed to give Renaissance shareholders a relatively higher price (and accept a lower value for their own shares) to make the Permira deal work. On the other hand, Michael Arrington publicly groaned about his "seller's remorse" after his big dollar deal with Arianna Huffington wound up putting him on the street.