I don't think the Mets have a choice about trading at least one of their "names" by the trading deadline. The Hardball Times ranks the Mets system as #24 out of 30 which, in my opinion, is accurate. In contrast, Baseball America ranks the Mets as #20, which I think is high. Because of those low rankings, it's critical for the Mets to improve their farm system. (It's uncertain right now how much of a difference the 2011 draft will make.) Thus, as I stated, the Mets need to trade at least one name.
I'd begin by trading Rodriguez, Beltran, and Pelfrey. Then, if I can get a "steal of a deal," I'd give serious consideration to trading Wright or Reyes, though I'd keep Reyes over Wright even though I'm still suspect of Reyes' performance this season as he's in his contract year.
What the Mets cannot afford to do is to not trade any of the above names.