Google opens up Gmail - requires mobile phone to sign up

Google has opened up its formerly invite-only Gmail service to the public, but you need a mobile phone to sign up.

Their have been some complaints about this, but I think it makes a lot of sense for Google to require some authentication to sign up for the service, both to reduce the number of spam accounts, and to act as a sort of two-factor authentication scheme in the future.

I'll post more about two-factor authentication and SMS next week.