I received a Circuit City Rebate check recently, from a camera I had purchased. In previous years, rebates would either never arrive or would takes months. This one took about 1 and a half months. I was surprised at the quick transit time. I doubt less than half of rebates ever get fulfilled. You have to follow the rules extremely carefully. Here's a few rebate rules I've seen.

You must have purchased the product within a certain set of dates. You need the UPC label, the receipt, and you need to fill out a form. The most annoying part is cutting out the upc label or trying to make a copy of it. The most difficult part is actually filling out the form. It's usually very difficult to fill out the form because the lines are so close together and they rarely give you enough space to write.

They also state that if anything on your rebate mailing is wrong, you don't get a rebate and they won't even tell you if something's wrong, they will simply discard your form. Rebates are a good way to save money but you must be willing to do a little work to get some money back.