The reason that 1st Gen iPhone owners were allowed to get the subisdized pricing on the 2nd Gen iPhone is that the 1st Gen wasn't subsidized. Anyone who bought a 2nd Gen iPhone had a subsidized price (initially at least), so they will probably not be able to get a 3rd Gen phone at the subsidized price until at least 18 months from when they purchased their 2nd Gen phone.
True but Apple wants every iPhone user to be able to buy the new one, think about it, if you don't have the New iPhone available for purchase at a good price ( maybe $100 extra for early upgrade fee ) then you lose alot of sales, and we know Apple loves toting there sales records. I can't wait to get it, I had the 3G since October, then had to give it up and just got a 1st gen as a back up. I may wait in line again for the 3rd time