libMesh is an open source finite element library that MOOSE heavily relies on. Because of this tight dependency, a version of libMesh that has been vetted by the MOOSE team is distributed directly with MOOSE. From time to time the MOOSE team will send notices out (using the moose-users mailing list) telling you that libMesh has been changed you need to rebuild it as detailed below.
To update your copy of MOOSE:
moosedirectory and run
git pull --rebase origin master
git pull --rebase upstream devel
After you have updated MOOSE go into the "moose" directory (if you're not there already) and run:
If your connection gets interrupted or fails in any way, you might receive errors when running the script a subsequent time. If this occurs, simply remove the libmesh directory an run the script once more. DO NOT delete your libmesh directory if you are using the internal SVN repository.
rm -rf libmesh scripts/update_and_rebuild_libmesh.sh
The libMesh documentation can be found here