The Philly-Houston trade is fraught with all sorts of intrigue. On one hand, it's typical - GM of new club ransacks the farm system of his old one. On another, it's a huge gamble for both teams, one with significant upside or crash and burn potential.
For the Phillies, the upside is obvious. With no starting pitching on the market this winter (and Kyle Lohse asking for $40M - Kyle freakin' Lohse!), the team's best option was to try to find a way to get Brett Myers back into the rotation. By picking up Lidge, they keep the back end of the bullpen strong and strengthen their rotation immeasurably. After all, there is literally no pitcher on the market this offseason who comes close to Myers when he's on. The one-two punch of Myers and Hamels at the top of the Phillies rotation makes them a much more dangerous team for 2008.
As for Lidge himself, a closer with home run issues going to CBP isn't going to see those get better. On the other hand, his raw stuff is still superb, and apart from LF and 1B there's going to be a solid defense behind him. So, there is some room for optimism there.
As for the Astros, they get Michael Bourn, who's been described as everything from the next Dave Roberts to the next Omar Moreno. What is dead certain is that he can absolutely fly, in a Joey Gathright sort of way, but with a little more pop in his bat. Whether he'll be able to step up to a starting role remains a question; he could be an above-average CF for five years, or he could be the latest in a long string of not-quite-good-enough-to-play-every-day Astros outfielders.
3B Mike Costanzo is another wild card. He's young, he hits the ball a mile, and he looks like he's finally figured out how to hit for decent average. On the other hand, he apparently bears the same relationship to defense that Bill Belichick does to fashion and he's only put together one really good year in the minors. So, he could be Steve Buechele, or he could be Brad Kommisk.
Geoff Geary's pretty much a non-entity, a middle-of-bullpen guy whom the Phillies will miss only when the rest of their arms start exploding again, and not through any special merit of his own.
So, in the end, the Phillies are gunning for the short term, the Astros the long. The Phillies' upside is limited but clear, the Astros' higher but far less certain. In other words, exactly the sort of thing that the Hot Stove League is made for.