This commercial aired during Comic Con 2009:
If you listen to it, they say that Oceanic has been operating since 1979, and has a 30 year perfect safety record. But the LOST plane crashed in 2004…. So the only way that the Oceanic statement could be true is that Jack’s plan worked! No plane crash!
This coupled with Hurley’s Mr. Cluck’s Video are a pretty clear indication that Jack’s plan changed a lot of things.
I’m going to write up some theories about what the implications of this are soon.