On the Astros site, they call it acquiring three from Philadelphia:

The Houston Astros today acquired outfielder Michael Bourn, third baseman Michael Costanzo, and right-handed pitcher Geoff Geary from the Philadelphia Phillies in exchange for right-handed pitcher Brad Lidge and infielder Eric Bruntlett.

…

“One of our goals coming into the offseason was to find a quality speed centerfielder who could hit at the top of the order and give us a spark,” said Wade. “Bourn is an outstanding young player who will make an immediate impact and should be productive for a long time. Plus, his addition allows us to move Hunter Pence to right field, where he will continue to grow into the All-Star caliber player that we know he’s capable of becoming.”

More importantly, Bourn coming to the NLC will give Reds’ broadcaster Steve Stewart yet more chances to make one of his favorite jokes:

You could say he wasn’t born yesterday…but he was.