Google has just added the iPad and the iPod touch support for the Google Voice iPhone app. The newly released Google Voice app version 188.8.131.526 lets you access our Google Voice account right from your iPhone, iPod touch or iPad. With this app installed on your iPad or iPod touch, you can make use of all the features of the iPhone version of this app (except making like cellular calls) sending and receiving text messages for free.
The new “Click2Call” feature, you can can an call to any of your phones right from the iPad or iPod touch. The other improvements in the new version of the app are auto-disabling of Text forwarding when the Push Notifications are enabled (to avoid multiple alerts for the same message) and the new “Do Not Disturb” feature (available under the Settings tab) that lets your callers directly connect to the voicemail when you are busy. Head over to iTunes App Store from link added below to download the app to your iPad or iPod touch devices running iOS 3.1 or later.
Download Google Voice App (via iTunes App Store)
[via] Google Voice blog