I use dotless 1.3.1.0 compiling less-files. This worked fine with bootstrap 2.x, but after switching to bootstrap 3.0.0 (downloaded the source from here: http://getbootstrap
One of my colleagues that uses dotless has had a few fixes for Bootstrap 3 issues merged. Apparently Bootstrap3 will now compile with the latest code :)
https://github.com/dotless/dotless/commits/master
I expect an updated NuGet package will be available soon (based on this tweet)