This instructions are meant to read twice before doing anything.
You can build mesa yourself, of course this will require lots of wits and brace yourself in case something goes wrong.
For this just download the mesa sources (you must make sure that the
deb-src entries in your sources.list are enabled):
wget https://launchpad.net/ubuntu/+archive/primary/+files/mesa_9.2.orig.tar.gz https://launchpad.net/ubuntu/+archive/primary/+files/mesa_9.2-1ubuntu1.diff.gz https://launchpad.net/ubuntu/+archive/primary/+files/mesa_9.2-1ubuntu1.dsc
Now we will need the building dependencies:
sudo apt-get build-dep mesa
Since the package is already debianized, it will give you a scapegoat to revert back any change made by the installation. Now we should extract our sources:
dpkg-source -x mesa_9.2-1ubuntu1.dsc
Now, we can build with
dpkg-buildpackage. The process will leave you with a bunch of
.deb files in the parent directory. You should install the ones that you need. Done.
If in any case you hit:
dpkg-checkbuilddeps: Unmet build dependencies: llvm-3.3-dev (>= 1:3.3-4) libelf-dev
dpkg-buildpackage: warning: build dependencies/conflicts unsatisfied; aborting
This means that your libraries are too old to build the package. You can download the file and install it from saucy at your own risk.
TL;dr: having the bleeding edge on software is nice, but it has it risk. I would wait until they get released in Saucy. (I'm using Debian and the package is already on experimental, so I just have to chill out for a bit)