Just in case anyone didn't get the memo, Google Voice is now open to the public. Yes, you heard that right. Anyone can now sign up and use it without an invitation: http://googlevoiceblog.blogspot.com/

Edit: Anyone with a US IP address can sign up. Sorry- posted this late at night and momentarily forgot there's a world outside the Continental US. Apologies to Europeans, Canadians and other citizens of the world if I got your hopes up.