I had no idea how dependent I'd become on git's stash function until I needed it while working on a project that uses subversion. I needed to make a quick change to a class to support a change to a schema change to a live server (don't ask), but I was already in the middle of working on another task.
Thankfully, you can approximate git stash by creating a patch file:
% svn diff > WorkInProgress.txt
% svn revert -R .
% svn commit -m "Patched to support server schema change"
% patch -p0 -i WorkInProgress.txt
% rm WorkInProgress.txt