CyanogenMod nightlies now let you use any messaging app for your Google Voice texts
Here's the feature, integrated in current (after July 1st) nightlies, in a nutshell: "The app will sync your existing Google Voice messages into your messaging store. New Google SMS will be received as if it were a normal SMS. When you send a message out from your messaging app, it goes out via Google Voice." Goodie. Head over to the source for installation instructions.
source: KoushikDutta (G+)