Jamey Newberg says the reports are Matt Nevarez and a PTBNL.
Nevarez is a nice live arm who is Rule 5 eligible this offseason, but wouldn't crack the Rangers' top 30 prospects, even with all the players graduating this year.
UPDATE -- Jamey says the Ticket is reporting that Jose Vallejo is the second player. Vallejo + Nevarez is...steep, for a backup catcher, but I'd guess that there were some off-the-field/p.r. implications behind the decision to bring Pudge back, as well.
And I have to think this is going to be viewed as a positive in the clubhouse, as well.
UPDATE II -- Evan Grant with some thoughts about the acquisition.
UPDATE III -- Brett Perryman has a rundown on Vallejo and Nevarez.