Google Mail now open for signups

Google Mail (GMail) has up until now been open to signups by invitation only. It seems they've opened up their process a bit and if you have a mobile phone, you can signup using that. It's interesting I was reading last night how the invitation process was perhaps a clever way to keep the spammers out.

The way this works is you enter your phone number, and receive a text message with the invite number, you then enter your invite number AND phone number and complete the process. This currently works with US mobile numbers only.

One thing I see about this that's troubling is that many cellphone companies charge for incoming messages and ... what if someone wanted to run up another persons cell phone bill...

Outside of that I think it's an interesting approach (should prevent automated or other bulk registrations (or at least slow them down).)