I ran across this Dashboard widget for Google Voice called GV Connect and it works great, it allows you to send SMS and make phone calls without having to go to Google’s website.  It also provides notifications for voice mail.  My favorite feature of this widget is the ability to pull directly from your Address Book and Contact lists by just typing out the name of the contact.  I highly recommend getting this application just for the ease of use alone.  You can also download it here.

GV Connect