https://services.google.com/fb/forms/googlevoicemilitary/

<< To help our service members communicate with their loved ones and show our support to those serving our country, Google is launching a new program. Starting today, any active U.S. service member with a .mil email address can sign up for a Google Voice account at www.google.com/militaryinvite and start using the free service within a day. >>

http://googleblog.blogspot.com/2009/08/audio-care-packages-for-service-members.html