We have confirmed with Valve that pre-orders will transfer properly to Steam! As you know, we have been funded largely by preorders although many of you have been patiently waiting to hear if pre-orders would let you download and play the game on Steam later. The answer is YES!
Pre-ordering now gives immediate access to NS2 mapping tools and artwork as well as early access to the alpha or beta when ready. We are now testing our engine with a small number of players and will expand that to everyone that has pre-ordered the Special Edition shortly.