The Hugin website has a page describing in detail the commands needed to install Hugin (actually, compile from scratch) specifically for Ubuntu. It does not need, or even discuss, Mono. I've now don this successfully on both Jaunty and Karmic, and am a happy Ubuntu Hugin user.
Apparently the Hugin developers are very happy to work with a C version of Autopano-sift and see no reason to pull in the additional overhead of Mono.