The BBC are reporting on news that Bet Fair, a bet exchange service that competes with convential bookmakers for punters money, is to enter a cobrand deal with Yahoo UK & Ireland. Betfair technology with Yahoo brand.

UK online betting exchange Betfair has signed a deal with Yahoo UK and Ireland, extending its betting platform to a mass market audience.

This is an interesting area as betting exchanges are not currently (though changes are occuring) licenced nor taxed in the same way that bookmakers are.
An example being this stat reported from The Register

online exchanges paid just £7.3m in tax last year despite taking bets worth more than £2.67bn. This compares to £376m paid by bookmakers on bets worth £30bn.