This price is for new lines only, and if you buy before 11:59 p.m. PDT tomorrow night, you'll get free activation along with the usual free two-day shipping too.
The upgrade price is still $179.99 (same as it's been since release day in June), which may not be low enough for EVO 4G users to make the switch, but for those looking to join the Sprint family, $99.99 gets you in with the newest, most advanced EVO in hand.
[AmazonWireless] Thanks, Doug!