mono-xbuild 5.18.0.240+dfsg-2ubuntu2 (amd64 binary) in ubuntu disco

 Mono is a platform for running and developing applications based on the
 ECMA/ISO Standards. Mono is an open source effort led by Xamarin.
 Mono provides a complete CLR (Common Language Runtime) including compiler and
 runtime, which can produce and execute CIL (Common Intermediate Language)
 bytecode (aka assemblies), and a class library.
 .
 xbuild is Mono's implementation of msbuild and allows projects that have a
 msbuild file to be compiled natively on Linux.
 .
 Microsoft Build (msbuild) is a build system developed by Microsoft similar in
 spirit to Nant (in that it uses XML files for describing the build process)
 and in the same spirit as make.
 .
 http://www.mono-project.com/Microsoft.Build