Santana is guaranteed $55 million through 2013 including a $5.5 million buyout for 2014. He hasn't pitched since 2 September 2010 when he allowed just one run in five innings against the Braves. If there are no further setbacks we might expect Santana to return to the Mets some time in August just in time for the stretch run to Spoiler Town.
Assuming the Mets go with the buyout in 2014, I was actually a little surprised to realize that Santana is only under contract for two more seasons. This is his fourth season in Queens and while the Mets haven't exactly gotten what we all thought they were getting (viz. one of the few best pitchers in baseball), to this point they've had three very-good-to-great seasons with two-plus seasons of TBD-quality remaining. That he only has two guaranteed years left means that if he pitches well enough in August and September and the Mets want to clear some payroll, they could realistically find a trading partner without having to pick up all that much salary.
On the other hand, if he looks good down the stretch they might want to hang onto him because good pitchers and cleanly trimmed Van Dykes are nice things to have around.