I am looking for a templating system for my forum
(http://rforum.rubyforge.org). I would prefer something lightweight like
PageTemplate over heavy XML stuff like Amrita, because the forum will
have to handle quite a lot of traffic and my server doesn't have too
much memory. But the reason why I can't use most of the templating
engines is that I want to make the forum multi-language, so that I can't
write:

[%if logged_in%]
Logged in as [%var username%]
[%endif%]

but would have to write something like

[%if logged_in%]
[%var text_logged_in_as(username)%]
[%endif%]

Does anyone know a templating system I could use?

Thanks
Andreas