Communication between Rails Projects?

Hello,

I have two Rails projects running on a single (clustered) host. What
the best way is for one project to access methods on the other
project?

My initial thought was to use something like Druby to make direct
calls to methods on the other project (if that is even possible). I
was also considering using web services or a REST interface, but is it
overkill to make HTTP calls when both projects are hosted in the same
place? Or can one project access another project's Rails environment?

Please let me know if I am on the right track or if anyone has a
better idea.

Thanks,
Peter