Hi,
I'm one of the lead of the EiffelStudio development platform (http://www.eiffel.com [1], http://dev.eiffel.com [2] and http://eiffelstudio.origo.ethz.ch [3]) and could not resist to try compiling our Eiffel compiler on Haiku. I'm pleased to report that I was quickly able to make it work with a few tweaks.
Have a look at my blog entry here for more details:
http://www.eiffelroom.org/blog/manus_eiffel/eiffel_on_haiku [4]
If anyone is interested in contributing, let me know.
Regards,
Manu