This is Why I Dislike Conf. Championship Games
I know they've helped LSU in both their national title years. In '03, Oklahoma lost to Kansas St. in the Big 12 championship which helped cement LSU's spot since they beat UGA. And in '07, their defeat of Tennessee added another ranked-team win to their resume and helped LSU jump from 7th to 2nd. It also helped UF jumped Michigan in '06 (they also jumped USC but that's because USC lost to UCLA).
So at least 3 times just this decade it's given an SEC team the chance to hop other teams. And really, I can't remember the last time an SEC team with serious national title chances lost the SECC. The favorite seems to win more often than not.