That Cameron did better than last time is not enough: he needed to obliterate the memory of the last bravura performance from Nick Clegg- and he couldn't do it. Although he tried to talk to the camera, he was more clunky- it was obviously something he had been told to do, and it looked uncomfortable. This was not the game changer that it needed to be for the Tories.
I think that the third debate will not be a game changer either. We will need to absorb the impact of the concerted Conservative smear campaign against the Liberal Democrats- which might end up hurting the Tories at least as much as the Lib Dems. However, it now seems highly likely that the Liberal Democrats are on course for a sensational result. What happens next is less clear, my personal view is that it is most likely that the next government will be a minority: and that will take us into a new situation in British politics.
Nick Clegg maintained momentum, and could not be disrupted by Brown or Cameron- in the end that is probably going to be sufficient to prevent the Lab/Con duopoly from continuing unchecked. The British people are showing their distrust of the power of the Lab/Con system and their disgust are where it has brought us.