Google has released a new way to use Google Voice on the iPhone. Just go to m.google.com/voice and it loads a slick new HTML5 interface.
via the Google Bloghttp://googlevoiceblog.blogspot.com/2010/01/google-voice-for-iphone-and-palm-webos.html
Google Voice on iPhone thru HTML5
http://googlevoiceblog.blogspot.com/2010/01/google-voice-for-iphone-and-palm-webos.html