Not automaticly, in any of the branches.
Once you have been "winged" you can take a test and you will be given a Comercial certificate in the appropriate catagory and class of aircraft.
:yeahthat:.
The test is the MCA (military competency-aircraft) or the MCH (military competency-helicopter). I took it about 5 years ago or so, and it was really easy. I think I studied a couple of hours over the course of a weekend and took it monday morning, and aced it in about 10 minutes.
Anyhow, you take the test and you get your commercial, multi-engine license and your instrument rating (for Air Force UPT, anyway). You will also get a type rating in the Beech 400 and the Mitsubishi Diamond Jet if you take it right out of UPT and you went T-1 track. If you take it from the C-12/T44 track I think you will get typed in King Airs, but I'm not entirely sure about that. If you go -38 track you will also be commercial multiengine, but it will be centerline thrust limited. Not sure about a type rating for those guys, either.
I waited a couple of years until I was in the KC-135 and my T-1 stuff was no longer valid, so I got my type in the B-707 when I did mine.
No matter what, you'll still need to get a single-engine add-on or get transfered to a single engine aircraft if you want to fly single engine airplanes on the civilian side.
BTW, there is also a new rule which lets us military instructor-types take a second "military equivalency" test and get your CFI, CFII, and MEI tickets, but I haven't done that one yet... so no intel.