Big League Stew's Alex Remington blogs on this subject today.
Using the 3 main sabermetric prediction models (meh) and his own experience and gut, he provides an answer that "Is Jeter the Greatest Shortstop Ever" posters may not like. First of all, he says Honus Wagner is the greatest shortstop, possibly the greatest player period, an opinion shared by some, but not all on the Jeter/Greatest post.
The predictive formulae all have Jeter barely hitting .300 this year, and regressing seriously defensively as well. BLS sees things a bit more brightly, agreeing with Bill James that a .317 batting average appears to be more in the cards, but that the big slip is coming fairly soon.
Given Jeter's work ethic, both offensively and defensively, and his opposite field hitting style, I think Jeter is as a good a bet as anyone to confound the historical norms for shortstop, but those norms are against him.