Derek Jeter's 10-Year $189 million contract signed in 2001 is up after this year. He wisely isn't sweating it publicly and is affirming his strong desire to remain a Yankee for his entire career. I'd be surprised if that didn't happen.
First off, the Jeter investment has by and large been a decent one. The idea of giving a player in his prime that long of a deal for that much money into his mid-30s might have seemed foolish, but he's been incredibly durable, improved his defense and put up MVP-level seasons at least twice. In other words, the Yankees don't have a lot of regrets for handing him the big bucks over the years. (Jeter has not gone the way of Nomar Garciaparra, Miguel Tejada or Edgar Renteria).
Second, Jeter is the most popular player on the team and already one of the franchise's historic icons in the line of Babe Ruth, Lou Gehrig, Joe DiMaggio and Mickey Mantle. Jeter should wind up with more than 3500 career hits and could sniff 4000 if he plays long enough. There's value in signing him beyond his on-field production.
Third, there's no way Jeter will get nearly as much money anywhere else. The Steve Henson article linked above suggests Jeter would need to get six years and $120 million. That seems awfully steep, and I doubt Jeter at age 36 would get anywhere near that should he go elsewhere. Both Jeter and the Yankees know this, and while he might be worth close to $20 million a year for 1-2 years, it's inevitable that his value will nosedive in years 4-6, especially given the likelihood that he becomes an OF or DH.
Bottom line, I'd expect Jeter to get a four-year $75 million deal taking him through age 40 - an overpayment, more than he'd get elsewhere, and worth it for the Yankees to keep him in pinstripes. (If the term were longer, I'd imagine the per-year salary would drop significantly).
Of course, Jeter's 2010 is a major variable. If he gets seriously hurt or slips noticeably (even on the defensive side), it will be harder for both sides to value his services and come to an agreement. Even then, I can't imagine Jeter getting more from another club than he would from the Yankees. If Jeter ever does play in another uniform, my guess is it'll be when he's in his 40s.