Sony has announced that sign-ups for the Infamous 2 user-generated content beta test are now open. US residents can sign up at the game's official site, and beta testers will get their invites starting in early April. The beta test itself will begin on April 12. Beta keys will be given in phases, so if you aren't in on the initial run, you might still have a chance to make some missions.
The blog post points out that you'll have to re-register for the Infamous site, so be sure to do that if you're interested. This round of the beta is only open to US residents, but other territories will get their chance as well.
The best missions created in the beta will be available on launch day for purchasers of Infamous 2. As revealed at GDC, the creation tools are pretty robust, and let users select templates as starting points like defense, escort, search and destroy, and survival. The PS3-exclusive Infamous 2 is set to hit on June 7.