Baseball America released the following yesterday:

Minor League Free Agents 2013

Scrolling down to the Mets you get:

New York Mets
RHP: Giancarlo Alvarado (AAA), Greg Burke (AAA), Matt Fox (AAA), D.J. Mitchell (AAA), Dylan Owen (AA), Armando Rodriguez (AA), Daryl Thompson (AAA), Cory Wade (AAA)
LHP: Justin Hampson (AAA)
C: Jeyckol De Leon (SS), Francisco Pena (AAA)
1B: Rhyne Hughes (AA)
3B: Richard Lucas (AA)
SS: Brian Bixler (AAA), Brandon Hicks (AAA), Josh Rodriguez (AA)
OF: Jamie Hoffmann (AAA)

Of those the most notable to me is Pena.  The 24 year old son of Tony Pena, was signed by the Mets in 2007 as an international FA with a 750K signing bonus.  After struggling offensively and moving slowly through the system for the first 5-6 years, Pena finally made it to AAA last year and seemed to benefit from the hitters climate.  

While the Mets have the most catching depth I have seen in TDA, Plawecki and Centeno it's always hard to lose capable catchers.  Pena has always been seen as a great defensive catcher but his offense must not be up to par. 

That being said, I would imagine the Mets would like to bring him back for AAA.  I would find it hard to imagine though that other teams wouldn't be interested.