With the git-rebase command, you can take the changes from one branch and replay them on top of another branch.
git rebase
allows you to specify the starting point of a branch, that is, to "move" changes from a branch on top of another branch. You can also specify specific commits even if they don't have branches associated with them
The Git book has a chapter on rebasing has some nice examples with diagrams that help to understand the general concept, although each system has different capabilities.
Another common way to integrate changes is to merge
to branches. The difference between these two operation has been covered in Stack Overflow:
Also on the usage of git svn
the equivalent to git pull
is a git svn rebase
that rebases local changes ahead of the commits existing in the subversion repository.
A rebase can be undone as explained in "Undoing a rebase"