It's not an easy call either way. Mike Griffin has always been afraid (with good reason) that money to extend the Shuttle's life past 2010 would mean cuts to the Constellation program. This news item states that a NASA report to be released today "projects that extending the program until 2015 would cost up to an additional $13 billion and could increase the chances of accidents with astronauts aboard." President-elect Obama's team has asked about a range of options, from extending the Shuttle to scrapping it on schedule and accelerating Constellation to killing the Shuttle AND cutting the scope of Constellation by scrapping the Ares booster program.
COMMENT: The last is, I think, the most likely outcome. While I never liked the Ares I and would be in favor of man-rating a Delta or Atlas launch vehicle instead, I think what will happen is that the whole Constellation program is going to be starved and stretched out while the Shuttle is retired anyway. I hope I'm wrong, but I'm quite sure that I'm not.