Ever since GV Mobile was pulled from the App Store, we've been hoping for its return. And while Apple has not approved that particular app again, they did approve GV Connect. It's three bucks, available now (only in the US) and looks great.
The app includes just about all the features you could want from a native Google Voice app, save for push notifications:
• Place calls using your Google Voice number rather than your mobile number - enter number directly, select a contact from your device's contacts, or call back any number in your history. • Send and receive text messages (SMS) from your Google Voice number. • Listen to voicemails and recorded conversations right on your device (allowing you to pause, rewind, or fast forward to any point within the message) - voicemails will also show the transcription of the message when available. • Mark messages as starred, attach notes to conversations, block/unblock senders, or delete conversations. • Easily search in your history by contact, message, or note. • Messages are stored on your device for offline access. • Composing notes and text messages can be done in landscape mode. • Quickly change various Google Voice account settings (call forwarding, do-not-disturb, message notifications, …) directly from within the application. • Automatic checking for new messages while the application is active. • Direct access to your device's contacts without needing to synchronize them with Google • All communication is done with the Google Voice website directly, no need to hand over your account information to a third-party. • Full support for fast app switching in iOS4 and high-resolution graphics for retina displays. • GV Connect stores your account password securely in your device's keychain for faster login when launching the application - communication is done via secure connections (SSL) to the Google Voice servers and no contact information (other than the contact's phone number which is required to place a call or send a message) is sent to Google. All operations are fully synchronized with your Google Voice account.