You'd probably not notice unless you were focused on US sports markets, but TradeSports has closed down. A message on their site essentially says they've given up as they were never going to make any money out of it.
Go back five years, there were probably about 40 betting exchanges out there including several white-labels. Without the liquidity, they will all fall over. Betdaq and WBX have been around for a few years now and still can't make much of a dent on Betfair, despite Betfair scoring a few own goals this year. Matchbook in the US is obviously proprietary backed in-running (prices set in-house, might as well be a bookmaker) much like Mansion tried to be. And there's a new joke-looking one advertising on Livescore at the moment - BetCruise, advertising no commission! Anyone offering odds on them going broke by the end of 09?