It's interesting scanning the Internets to read about the Mets' front office reaction to the news that Barry Zito won't be coming to Queens. This site offers the following:

There's little doubt the Mets have interest in some of the A's young pitchers, and should they finally decide to part with outfielder Lastings Milledge and one or two of their promising young pitchers (Aaron Heilman, John Maine or Mike Pelfrey), it's possible that New York would offer a better package for Joe Blanton. (New York's first choice would be Haren, but to get that trade done, one major-league executive speculated recently, "the Mets would have to back up the truck.'')
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It would be unwise to shoot a Mets bullet like Lastings Milledge now and find you need him in June or July to solve another need. The advice here is to obtain a proven innings-eater such as Baltimore's Rodrigo Lopez, who like Bronson Arroyo would benefit in going from the AL East to the NL and would not cost much in a trade, plus sign a high-risk, high-reward type such as free agent Tony Armas.
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The Mets want to trade for a starter. But the White Sox do not appear ready to move another veteran. The A's would have to be overpaid to part with even Joe Blanton, much less Dan Haren or Rich Harden. The Mets don't like the Dodgers' Brad Penny or Philadelphia's Jon Lieber. Minaya concurs that it will be a "long shot" to pry an impact starter. But the Mets do not need to do that now.

And mlbtraderumors has this:

One option is to hit up Billy Beane for Rich Harden or Danny Haren.  Bob Klapisch reports that Omar Minaya spoke to Beane ten days ago, hoping for a deal of Aaron Heilman and Lastings Milledge for Harden.  Beane countered with Carlos Gomez and one of Milledge/Philip Humber/Mike Pelfrey.  Those talks are proposals are pretty far apart.

Let's just focus on those A's pitchers for a minute. Joe Blanton is 26 years old, and in 2006 he went 16-12 with a 4.82 ERA as opponents hit .309 against him. Dan Haren is also 26 and pitched better last season, going 14-13, 4.12 with an outstanding K/BB ratio of 176/45. Rich Harden is 25 and went 4-0, 4.24 in an injury-shortened season, but looked for all the world like an emerging ace in 2004-5 with a combined 21-12 record and nearly a strikeout per inning.

All things considered, Haren is probably the prize of the group; Harden's got as much or more upside, but his health questions probably depress his value a tad. Even for Harden or Blanton, Beane evidently won't take a combination of Milledge, one of the more complete outfield prospects in the game, and Heilman, who could start or set up for most teams. My prediction is that if the Mets and A's do get together on a deal, it will be Blanton or Harden for three of the Mets' top prospects--Milledge or Gomez, Pelfrey or Humber, and another arm further from the big leagues.

Compare this to the deal Pat Gillick made in trading two probably lesser prospects (depending on how much you like Gio Gonzalez) for Freddy Garcia, whose career performance has compared well to that of any of the A's starters. Garcia's more expensive, of course, and he's just a year from free agency. But to a team like the Mets, with essentially unlimited resources, neither of those considerations count for much. And they'd probably prefer a somewhat older guy who's pitched and won in the postseason to a kid who's thrived in the low-intensity Oakland market but has yet to be tested on a bigger stage.

It's hard for me to believe that the Mets couldn't have made a better offer for Garcia than what Chicago took from the Phils. Maybe Omar Minaya, whom I think is a pretty good GM for that team, was so fixated on Zito or other options that he didn't pursue a deal with the White Sox as adroitly as he could have. Maybe Minaya and Kenny Williams don't mesh well. But whatever the case, today it looks like the Phils might have gotten a big win over the division rival they're chasing.