Since Google hasn’t released an official Google Voice dialer for Windows Mobile, gVo could be your best variant. It's AssassinsLament who decided to make a Google Voice dialer for Windows mobile.

Features:

- Select contact and dials their Number (Mobile);
- Enter in a non-contact number and dials;
- VGA Only;
- Skin support;
- Limited landscape support;
- Calling Card Method;
- Google Online Functions - SMS/CallBack/Inbox/Voicemail (NEW)