pilcrow: That double-stemmed backward P symbol used (most often in proofreading and editing) to indicate the end of a paragraph and the beginning of a new one. Or, more succinctly, the symbol in the above rebus. Wired magazine sometimes uses the pilcrow character (in a lighter color) to mark the end of a paragraph without actually breaking to a new line. A great space-saver.
One thing I don't understand about the pilcrow: Why doesn't the word appear in either Webster's New World Dictionary or Merriam-Webster's Collegiate Dictionary?