The '80 election parallel is also invalid unless Obama gets his own hostage crises. He might have weathered the economic downturn (stagflation) with the help of the media, but the hostage crises and the final debate performance by Reagan turned the late polls against Carter very strongly. There was the one overnight tracking poll done on election eve that showed Reagan's lead blowing open again. It was clearly related to the hostages.
Obama isn't very smart on his own, but I think he will likely avoid the mistakes Carter made. No doubt the media will savage any candidate put up in opposition to their Messiah, but the knives are out for Palin in double portion.
The Iran hostage crisis began a full year before election day. Carter's failure to deal with it was a given throughout the campaign season. Even so he looked like a winner over Reagan. The NYT editorial page gassed on about how events in Iran proved we couldn't afford a clodhopper like Reagan in the White House. Six months before election day, the smart money said the hostage crisis would work to Carter's advantage because voters wouldn't trust an untried simpleton with the leadership of a turbulent world.
In the end the crisis certainly contributed to the sense that Carter was a failure, but he would have been judged a failure without it because he was a failure. He couldn't hide it and Obama won't be able to either. The lesson of 1932, 1968 and 1980 is that failed presidents lose. The events of each case will be different, but falure in office nearly always means failure at the ballot box.
It doesn't much matter whom the GOP nominates. The election is Obama’s to lose and right now I'd say he's doing a great job of losing it.