No one really knows.
Some say AT&T are going to stick it to you just like all of the other cell phone customers and make you pay full price.
While others say it is clear that Apple and AT&T have a special relationship unlike any other in the cell phone business. So the old rules might not apply.
My feeling is that the price points will stay the same for one main reason...The numbers don't lie, hundreds of thousands of more people bought the 3G due to the fact it was so much cheaper. Many of these people will want to upgrade to the new, flashy hardware but would never drop $500 or $600 dollars on a phone. Telling all of the people who bought a 3G iPhone "sorry, your going to have to wait a year if you want this at a decent price.." is a bad business plan.
I think the people who write "3G owners are SCREWED!!11!" are probably smug 1st Gen owners who after two years on edge, feel vindicated in their cheapness.