So I finally decided to upgrade my linux server to the latest Ubuntu, Mono and BlogEngine.NET.
As you can see it all worked out in the end, but only after 2 days of fighting trying to compile Mono 2.2. Let me point out though that it should not have been such a mission. Mono 2.2 does compile and install fine using the instructions you can find here.
The snag turned out to be the amount of memory available on my VPS. So here's a note of warning to everyone trying to compile Mono 2.2: You need more that 300 MB of RAM to make it work. Anything less and you're going to end up with the compilation process dying at random points with no indication as to the problem. 400 MB eventually did the trick.
As for BlogEngine.NET 1.4.5, it works fine on Mono except for the URL rewriting. A fix for that is available here.