Obama famously claimed that "you didn't build that" when talking about how no one creates success in isolation from the community they live in. They don't perform a solo act and they should give back, was his argument.
It is hard to imagine Donald Trump, for instance, having his great success on a desert island. Wait. No. Donald Trump is self-contained enough that it's easy to imagine him even having his own TV show on a desert island. Bad example. But most people build on and draw from others to create success, dependent on the community.
I was listening on the radio and missed the graphics but it seemed like the sound bite of Obama saying, "You didn't build that" was being played at the convention at the transition between speakers who praised Mitt Romney. They talked about how Mitt saved, not just the Salt Lake City Olympics but the very Olympics themselves. They talked about how they started a business but were lost before Mitt came along.
And in those stories I heard a new variant on "You didn't build that." What I heard was, "You started a business? You didn't build that. Mitt did." "You won a gold medal? You didn't win that. Mitt did."
I initially thought that Romney's disapproval of Obama's line was that Obama seemed to be denying credit to the individual. Turns out, Romney was just disappointed that Obama was denying Romney credit.