I would say pilots from other services make up a significant percentage of our aviation work force. We often hold DCA (Direct Commission Aviator) boards where already winged pilots from other branches submit packages and apply for slots in the CG.

Generally speaking if you were an O-3 or higher in another service you will be dropped down in rank to O-2. Conversely if you were an Army Warrant officer you would enter the CG as an O-1. I have heard rumours that this policy may have changed and you can keep your former rank but I'm not to sure on those details.

Since being in the CG I've met pilots from all of the other services that have made the switch. I'm not real familiar with application process but I believe on the CG's web page there should be some more info.