Multi Site logins

[VecSignia]

Hi,

We've got two sites both running their own licenced installs of vB5, both sites are on the same VPS, and they are both car related sites. One site is 11 years old and has several million posts, and the other is a new site setup last week. What we'd like to do if possible is to allow members of the original site use their existing login and username to access the new site which caters for the more recent model of the car.
I see that on vB4 their was a bridge called cerberus. Would this still work in vB5 or is there an alternative.

Any help would be gratefully received

Regards
Pete