The Philadelphia Phillies needed a bat to solidify their lineup, specifically in the five hole behind Ryan Howard.
Houston gets first baseman Jonathan Singleton who can also play the outfield. They also picked up minor league righties Jarred Cosart and Josh Zeid. A player to be named later is also going to the Astros.
Pence, who played the first four and a half years of his career in Houston, now starts in right field for the Phillies, with Dominic Brown going down to AAA to play every day.
The Astros get the Phillies top two prospects in Cosart and Singleton. Both should help Houston a lot in the future. Singleton will probably have to play the outfield with Brett Wallace flourishing at first.
A quick recap-
Phillies Acquire- OF Hunter Pence

Astros Acquire- Class A 1B/OF Jonathan Singleton, Class A SP Jarred Cosart, AA RP/SP Josh Zeid.

After all this it seems clear the Phillies will be extremely scary come October.