(some of the stars got stripped by HN so the above won't work)

Try putting a couple of spaces in front of your code line, like this:

  cat file | perl -p -e "s/.*from ([0-9\.]+).*/\1/g"

See http://news.ycombinator.com/formatdoc

Edit: for simple regexes, sed works well, too, and probably loads slightly faster than perl.