Nope. Beta build is in the works. You may notice that they say "we cracked the lid off our pre-alpha build" of something like that. Basically, Bungie has the pre-alpha version of the game saved as its own file, and when they start on the alpha, they take that file and edit it and save it under a different name. then they do the same thing for beta, and then the same again for their launch version. At any time they can load up a previous version of the game and play it. They're showing off the pre-alpha version because it's stable and not buggy, and while the alpha version is probably the same way, the pre-alpha versino has less goodies for media outlets to accidentally come across and report before bungie is ready to release them.