First I want to say Thanks to Xamarin for providing packages now for Linux again. I am personally using the Mono packages from Xamarin for CentOS7, and the MonoDevelop package for Ubuntu from Xamarin.
I have decided I will not build my own MonoDevelop packages anymore, since the Xamarin packages are sufficient.
There are also some issues that I could not figure out, so at the moment my MonoDevelop packages on OBS do not build at all. I have no intention to fix them, because there is no need for them.
For example, to install the latest MonoDevelop on Ubuntu, you can follow these instructions (see also http://www.monodevelop.com/download/linux/#debian-ubuntu-and-derivatives):
apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF echo "deb http://download.mono-project.com/repo/debian wheezy main" | tee /etc/apt/sources.list.d/mono-xamarin.list apt-get update apt-get install monodevelop monodoc-browser
I also wanted to stop building the Mono packages for various Linux distributions, but there are issues for CentOS6 with libgdiplus and libpng15 with the Xamarin packages (http://lists.ximian.com/pipermail/mono-list/2014-October/051241.html), so I will keep providing Mono packages at the moment.
The latest Mono packages for 3.12.1 are available according to the instructions at http://software.opensuse.org/download.html?project=home%3Atpokorra%3Amono&package=mono-opt
I have added packages for Fedora 21 there recently.
I have also worked on getting Mono 3.12.1 built for CentOS5. This required to use a newer GCC than is available on CentOS5. This meant I cannot build it on OBS since it is not allowed to link in different repositories. Obviously I could try to build a newer GCC on OBS as well, but then it becomes more and more complicated, and others have done this work already (http://people.centos.org/tru/devtools-2/readme)
The solution now works with my own LightBuildServer, and the result can be seen here: https://lbs.solidcharity.com/package/tpokorra/mono/mono-opt
If you want to build Mono on your own LBS, let me know, and I will improve the installation instructions for the LBS. All the code is public already, at https://github.com/SolidCharity/LightBuildServer/
The sources for the RPM packages are maintained here: https://github.com/tpokorra/lbs-mono/tree/master/mono-opt
If you need some paid assistance with Mono packages for your distribution, please contact me via ODesk: https://www.odesk.com/o/profiles/users/_~01e826605fea50faae/