I applied in-person. The process took 5 weeks. I interviewed at US Postal Service (Phoenix, AZ) in Jan 2008
Interview
You must first take a test that gives you a score from 1-100. You get extra points for being a veteran. If you score well (over 85) you will typically get a call back to come in as a group of 20-60 people. They then whittle it down based on scores and only interviews people that are called back.