[dannyr]

I'll argue to the contrary.

Lots of sites use Facebook Connect because it actually drives signups.

Where are you basing your argument that people do not actually want to give their twitter username and password?

In my experience, a lot of casual users do not actually care. We had an email inviter that was used frequently where people actually have to give out their Gmail/Yahoo/Hotmail credentials.

You may be comfortable with user/pass but do not make the assumption that the rest of the world are. You may think you're mainstream but you're probably not.