A more serious take on the problem noted below, from Time's Scherer:
McCain's campaign is resigned to the fact that late night comics are foaming at the prospect of six more months worth of old man McCain jokes. And polls show that the Republican's age — he will be 72 by Election Day — could have an impact at the ballot box. But both McCain and his advisers have been pointing to a prospect they hope will neutralize the issue: a relatively youthful vice president, who might lesson the fear of, gulp, McCain's death in office. "I'm aware of enhanced importance of this issue given my age," McCain told Don Imus recently, when asked about his vice presidential pick. A few weeks later, campaign adviser Charlie Black elaborated on the assumed power of a solid vice presidential candidate. Back in 1980, Black recounted, Ronald Reagan was running for president as an older man at 69. "The day he picked George Bush to be vice president, the age issue pretty much went away," Black recalled. "If [McCain] makes a good choice, that might alleviate the issue."
P.S. McCain's 72nd birthday falls on August 29, just before the September 1 start of the GOP convention. I suspect there won't be a big photo-oppy celebration. At least it doesn't fall during the convention, I guess.
--Michael Crowley