Google Voice is as of today open for everyone:
http://googlevoiceblog.blogspot.com/For those of you who want an easy to use, always accesible and -- best of all -- FREE voice, voice mail and SMS Internet-based telephony with a permanent phone number, Google Voice is a nice alternative. Domestic in and outbound calls are free, and international calls have very low rates (e.g. 2 cents / minute to Buenos Aires landline).
It has a ton of other useful features also -- like call forwarding to multiple numbers, voicemail transcription, bla bla bla.
Sign up here:
http://www.google.com/voicemh