It should be soon available in maven repositories thanks to Sonatype services.
For the impatient:
Thanks to Jeroen Frijters we'll be having soon the dlls that can be used in .net with the IKVM runtime. Check http://www.ikvm.net/ for more details.
We are adding many new APIs to better support creating and manipulating messages.
We also have in our pipeline migrating to git.
MX support is coming soon too