Passenger returns .haml source code

I ran into a strange problem when upgrading a app to Rails 2.1,
Passenger 2.0.2 and HAML 2.0.1.
On the production machine, haml views are not interpreted anymore, but
rather the haml source is sent to the browser. Erb templates are
rendered/interpreted perfectly. Even when I render a haml-partial inside
a erb view only the haml part is spit out as source code. Are there any
issues when running haml and passenger in the current release?

Any Ideas?