For those that pre-ordered the special edition of the game the launch date for the first Alpha test has been announced, July 26th.
NS2 Alpha 1 content
• One of our shipping maps (ns2_tram), plus some smaller "test" maps
• Marine, with Rifle, Pistol, SwitchAx, Grenade Launcher
• Skulks, Gorges, Lerks and their basic movement abilities and weapons
• Marine armory "buy" screen for purchasing new equipment
• Alien evolution menu for choosing your lifeform and upgrades
• Basic marine and alien commander interfaces including MACs, Drifters
• Much of our final sounds, artwork, animations, etc.
SOURCE NS2 Alpha date set! - Natural Selection 2 News