Stop-loss has been around for many years. I was familiar with the concept when I was on active duty, and it has been over 7 years since I got out.
It makes sense. During time of war, the routine ETS (end of service) are stopped. No fun for the soldiers, especially with a rolling conflict like Iraq--but then I don't think there is a automatic stop-loss in place for that contract, as I know plenty of soldiers who have gotten out in the past several years.