Obama has indeed worked on ethics reform the past two years, which came in the aftermath of the Abramoff scandal amid a groundswell of support for reforms. But the other Democratic candidates have backed reform as well. It's an exaggeration for him to suggest that he was the only person on the stage in Philadelphia who had pushed for reform.
Last year he cosponsored an ethics reform bill and was the Democratic point man for drumming up more cosponsors. Joining him in cosponsorship were his debate mates, Hillary Clinton, Chris Dodd and Joe Biden. That bill did not make it out of committee, but another, less stringent, ethics reform bill did pass the Senate.
That bill, authored by Sen. Trent Lott, R-Miss., passed, but Obama can't take credit for that one. He didn't even vote for it because he objected to the lack of enforcement provisions.
He did cosponsor a successful amendment concerning meals from lobbyists, but the main sponsor of that amendment was the allegedly inactive Dodd. Clinton, Dodd and Biden voted for the final bill. This year Obama cosponsored (and according to his campaign, helped draft) a bill further tightening ethics rules for Congress. Russ Feingold introduced it Jan 9, 2007. However, it was not that bill, but another one, sponsored by Majority Leader Harry Reid and introduced five days earlier on Jan. 4, 2007 that eventually became law. Obama was not a cosponsor, but he did successfully offer an amendment concerning lobbyist disclosure and the bill included some elements from the one he had introduced the previous year. Obama, as well as Biden, Clinton and Dodd all voted for it. In the House, Kucinich also voted for it.
And so, given that Obama had some help with ethics reform, we rate his statement Half True.