e8johan: The answer to your question is both yes and no. Yes, sure it is a plus, but on the other hand there have been and is lot of other options for easier OO in GNOME using C++, Python and Java for instance. So concluding that Mono developments main attractiveness is due to easier OO is probably much to simplistic. I think it is more that people feel that with Mono the platform is actually taking a big step forward; ie providing more than just some extra programming language gloss. That Miguel is a good advocate probably doesn’t hurt Mono either :)
That said I think the position of Python as a programming language in the GNOME community is understimated. Considering that Red Hat seems to use it for most of their stuff, Ubuntu is using it for their stuff, my own company Fluendo is using it for our stuff, and of course a lot of independent developers are using it, I think that Python is probably the most widely deployed development language for GNOME apart from C.
Pointing back to the mono discussion I guess Miguel would be fast to point out that you can easily tie inn Python stuff to Mono using Iron Python. Although afaik no of the main commerical or independent users of python are doing so yet :)