Touted as a potential Google-Killer, PowerSet has been piquing interest but has remained in a closed alpha. I just got an email today saying that it is now opening to a wide-scale beta and that invites will be sent out in the order that people signed up.

"This is an exciting time for Powerset Labs! We announced at TechCrunch40 that we've begun the process of releasing Powerset Labs to the public. About 100 close friends and family of Powerset have been using Labs for about a week now and Powerset will be inviting additional users into Labs based on the order you signed up. We've been overwhelmed with the demand to try out our technology, so we're letting people into the community slowly to make sure that everyone gets a great experience and that the community builds organically. In fact, we've already begun to implement ideas from our first 100 users, which will help to improve the site when you get your invite! We'll get you your invite as soon as we can."

For the moment, the index is restricted to Wikipedia, so it still has to scale to the whole web.

http://blog.powerset.com