one practical usage example of xargs:

… to process every file that find found further
# this would backup/pack all jpg files on your system into all.jpg.tar.gz
find / -name „*.jpg“ | xargs tar -czvf all.jpg.tar.gz
# delete all jpg files of your system (DANGER :-D)
find / -name „*.jpg“ | xargs rm -rf
# okay this could also be done with
find / -name „*.jpg“ -delete

# but now:

# output list of all files on your system that contain „Torvalds“
find / -type f | xargs grep -i -s -l „Torvalds“;
# -i = ignore case
# -s, –no-messages = Suppress error messages about nonexistent or unreadable files.
# -l, –files-with-matches = Suppress normal output; instead print the name of each input file from which output would normally have been printed. The scanning will stop on the first match. (-l is specified by POSIX.)
which lead to where you can basically watch Torvalds at work 😀

also found on SUSE12: SubmittingPatches.txt