You will be reimbursed for everything directly associated with moving (U-haul, boxes, milage, etc). I've heard of people using moving companies and getting reimbursed but I'm not sure whether it was in full or not. You submit an estimate before you move along with your reciepts after you're done and they cut you a check. I've never heard of anyone getting screwed after going over their estimate. I can't remember if we get per diem for moves and our intranet is down so I can't look it up.
Hotels and moving time are the big complaints with the moving policy. You will get 1 day for every 300 miles you have to drive. When you take it is negotiable-- most people couple it with days they would have off anyway so they get some extra time. Airnet will pay up to $50/day for hotels but only days you actually use-- in other words, you have 4 days to move but are able to drive it in two, you are only getting reimbursed for $100. They do not pay for a hotel while you look for a place; that is an old policy and I'm not certain when it changed.
Personally I think it sucks that you should have to spend money out of pocket to move for the company but they'll usually work with you to make the logistics work.