I don't think you need to be invited any more, you can just set it up. You'll find it on this page, and if you also download and install the Google Toolbar then you'll have an icon on the top of your browser to show you if you have email. I've also used the iGoogle settings to customize my home page with my favorite links, etc.

http://www.google.com/intl/en/options/

I think once you have your gmail account set up you can go back to your Yahoo account and set it to forward all mail to your new Gmail account. I've found Gmail to be a lifesaver as I switch away from the earthlink mail I've used for years.

SRS