I just signed up with my domain account and I did not give them my password, although on their site they state that they need it for Google Apps accounts. Pretty odd.

It's still in the 'setup' state so I can't really do anything in their UI yet but it did let me login with my google apps email never the less.

If you set up a Google Account with your domain email address wouldn't that explain this?

I'd like to know too. My primary personal account is on Google Apps.