Yes, Clegg won the debate. But Cameron is, by far, the big winner tonight. As much as the Lib Dems may have made big moves, whether it's right or not (it's not, btw) the fight is between Labour and Tory, and David Cameron won that particular fight by a long way.
Brown appeared to have a tactic of attack Cameron, try to appear cosy with Clegg and hope the piggy-in-the-middle offensive worked. It didn't. Every time he said "I think Nick and I are in agreement" or "Nick agrees with me" or "Nick supports our policy", Clegg slapped him down and left him looking stranded, desparate and out of his depth. Cameron appeared calm, assured and comfortable.
It depends on how you would categorise a win, but without a shadow of a doubt, for me, Cameron got the most out of it, and what he'll have got is votes at the expense of Labour.