From Huffington Post:
[D]isatisfaction with the course of the war under President Bush and with the treatment of veterans returning home has given Obama, who did not serve in the armed forces, an opening with military voters and veterans. So does his appeal to younger people.
That Obama attracts support from some in the military is evident in dollars and cents: Among people who have donated at least $200 to a presidential campaign this election cycle, Obama has collected more than $327,000 from those identifying themselves as military personnel, while McCain has collected $224,000, according to an analysis of Federal Election Commission data by The Associated Press.
Read more here.