Several months have gone by and the issue remains unresolved. However, today Google made good on its promise to bring its call routing and calling service to the iPhone "one way or the other" by unveiling a new web-based version that leverages HTML 5's functionality for quick access to Voice's most important features.
The company already had a version of the service available through mobile web browsers; albeit a pretty limited one. The new version is much more interactive, with the ability to listen to voice mails directly from within the browser and to dial phone numbers on an interactive on-screen keypad. You also get access to voicemail transcriptions, free SMS, and of course the ability to answer all of your phone numbers from a single handset. Unfortunately, the web app cannot access your device's contact list so you'll need to import them.
It should be noted that this version of Google Voice has also been optimized work with Palm's webOS devices, and will work with any other HTML5-compliant device, although the formatting at this point has been tailored to Apple and Palm's platforms. Simply go to m.google.com/voice to make cheaper calls from your device.