From a visual evaluation of manually entered license descriptions in Launchpad on March 25th, this a rough count of licenses split up into a few categories:

  || Creative Commons (one of SA, ND, CA) || 58 ||
  || Creative NC || 15 ||
  || GNU FDL || 13 ||
  || Proprietary or internal || 6 ||
  || Not decided yet || 30 ||
  || Multiple or nondescript licenses || 56 ||
  || Other standard license || 162 ||

Of the other standard licenses described in the text field, this is a simple breakdown:

  || zlib || 11 ||
  || Cecill || 6 ||
  || Boost || 6 ||
  || WTFPL || 5 ||
  || Microsoft PL || 4 ||
  || Ruby || 3 ||
  || Artistic || 2 ||
  || TGPPL || 2 ||
  || W3C || 2 ||

This breakdown is of a total of 399 projects with license text listed; a number of projects were disabled as part of this exercise.