First off, the Pre is $199, not $299. Yes, if you buy from a Sprint store you have to deal with a rebate, but you can get it for $199 out the door at Best Buy.
Second, the comparison is invalid because the Sprint plan includes unlimited text. Very few smartphone users go without a texting plan. Also, Sprint unlimited night minutes begin at 7pm, AT&T at 9pm. AT&T has rollover minutes, but I think the average user does better with unlimited after 7pm than they'll do with rollover.
If the bare minimum plan is okay and you never send a single text, the plans are roughly equivalent. Once you get into the plans a large majority of people will use, Pre + Sprint saves a lot of money. Whether it's $480 or the number Sprint's claiming.