Transparent user session over several sites (single sign-on + single sign-off)

Question

I have several sites in different domains: example.com, example.org, mail.example.com and passport.example.org. All of th

Answer 1

A cross domain capable rails plugin to do this would be awesome.

I'd like to do it, the only way I could think of was to force the user to download a toolbar, or some little air app that would handle logging in automatically for me.

I'd love to know another way 'cause that blows