Per the beat guys on Twitter, the Rangers exercised their 2014 team option on closer Joe Nathan, but Nathan exercised his right to void the option, and is now a free agent.
Because Nathan finished 55 games in 2013, he was able to void the Rangers' $9M team option for 2014, and his doing so was expected. The Rangers would have owed Nathan a $750,000 buyout if they had not exercised the option. Because they exercised the option and Nathan voided it, they have saved that buyout.
Nathan did a terrific job as the Rangers' closer in 2012 and 2013, after having been signed as a free agent prior to the 2012 season. Nathan is reportedly seeking a multi-year deal, and Jon Daniels has publicly indicated that they do not anticipate committing to a large multi-year deal with Nathan.
Likely candidates for the 2014 closer's job with Texas are Tanner Scheppers, Joakim Soria, Neftali Feliz, and Alexi Ogando.