I'll offer some thoughts to Brad's post below before focusing on the trade that the Twins actually made yesterday. I don't think the Johan question is a simple yes or no. Should the Mets trade Jose Reyes for him? No. If they could simply part with Carlos Gomez and Mike Pelfrey, then the answer would be yes. I'm glad the Mets are at least in the hunt, but in the end, the Red Sox and Yankees are better matches for the Twins. Now that the Twins have Delmon Young, they probably want a young pitcher to be the focus of the Johan trade. The Mets' best prospects are outfielders; the organization doesn't have any pitchers that come close to Joba, Hughes, Buchholz, or Lester.
In the end, Haren may wind up being a better option. Johan is the best pitcher in baseball, but Haren is a pretty damn good pitcher himself. The difference between the two is probably about 1.5-2 wins per season. Rumor is that Johan is going to demand a contract extension in the neighborhood of $120-150 million for 6 years. On the other hand, Haren is already under contract for three more seasons at a very affordable price. If the Mets make a move for Haren, they'd still have the money to make a run at any free agents that hit the market next year. Sabathia? Sheets? Mark (not a pitcher) Teixeira?
Hard to tell what it'll take to get Haren because unlike the Twins, the A's aren't in a position where they have to trade him. So, it might not be easy to pull off a deal. Maybe something like Milledge, Heilman, Mulvey? I'm not sure that'll get it done, might have to include two of the three young outfielders.

It seems like most trade rumors these days involve situations like Johan and Miguel Cabrera where a team can no longer afford its superstar, so they trade them to a team in NY, LA, Boston, or Chicago. Fun for the sports talk radio stations in those cities, but kind of depressing for the fans of half the teams in the league. So, it's exciting to see a big trade that has nothing to do with money - two small-market teams trading top young players for each other. Delmon Young, Brendan Harris and Jason Pridie for Matt Garza, Jason Bartlett and Eduardo Morlan. Delmon Young for Matt Garza is the big story. They're both very talented young players, but Young is superior. Both Baseball Prospectus and Baseball America ranked Young as the #3 prospect in baseball last year. They disagreed a little bit more on Garza; BP ranked him #13 while BA ranked him #21. Both players were a bit disappointing this year, but are still among the top young players in baseball.
It's a ballsy trade for the Devil Rays. There's a decent chance Young develops into a true superstar and winds up in Cooperstown. In that case, the deal will wind up looking pretty bad for Tampa. Young is indeed quite young. Few players play full seasons in the majors at the age of 21, but he still has some serious holes in his game. His terrible plate discipline was the cause of his below average performance at the plate. He has a strong arm, but is not a very good fielder. A lot of people have compared him to Sammy Sosa, which may excite Twins fans until they realize that if he follows Sosa's career path, he'll already have left via free agency before hitting his prime.
Garza, on the other hand, doesn't have future superstar written all over him, but seems a good bet to be a solid major league pitcher. He'll probably be a #3 starter, maybe a #2. The Devil Rays had two very good starting pitchers last year and a bunch of horrible ones who cycled through the last three spots. They have some good prospects on the way, but Garza can step into the #3 spot in the rotation right now.
The swap of Harris for Bartlett will help the Rays' defense tremendously. Harris had a very nice season at the plate, but he's not really cut out for shortstop. The Devil Rays don't have anywhere else to put him in the infield. Their defense was bad in general, so adding a strong defensive shortstop will help the young pitching staff a lot. All the leading defensive metrics rank Bartlett as one of the best in the league. He's probably an upgrade of at least 2 wins defensively over Harris. He might give one of those wins back at the plate, but Bartlett has been pretty solid (for a SS) with the bat the last 2 years.
So, I think this trade makes sense for both teams. The Twins are on the verge of trading Johan (and possibly Nathan) for prospects, giving up on 2008 for a chance to be a contender in the future, possibly as soon as 2009. I have some doubts about Young, but he has the chance to be a superstar, so it's a good roll of the dice for the Twins, who will probably be able to stock up on young arms to replace Garza.
The Devil Rays have a lot of young outfield talent. They need another good young pitcher and a strong defensive shortstop. Also, Morlan has a chance to be a very good relief pitcher in about a year. The Devil Rays will almost definitely be a better team this year because of the trade. If they played in the NL Central, they'd be a contender. Unfortunately, they play in the AL East, where they're still lightyears behind the Yankees and Red Sox. Some will argue that the Devil Rays shouldn't be worried about the difference between being a 70 win team and an 80 win team, but for a team that has never won more than 70 games and is looking to build a new stadium, I think there's something to be said for fielding a .500 team. Three cheers for mediocrity!