“Freebase.com is home to a global knowledge base: a structured, searchable, writeable and editable database built by a community of contributors, and open to everyone.” That last part isn’t currently true. You need an invitation to get in to the Freebase Alpha.
I remarked in my earlier post about Freebase that I didn’t have any invitations to give out. Well, I do now (and so do other existing users). A comment here, or an email (andrew at changingway dot org) will get you one, if you’re quick enough.