A very interesting discussion, the only knowledge of blue blood I had was that of claims made by European royalty.
On the second wikipedia entry it ended "there is another legendary version saying that John the Baptist refused sexual propositions from Herodias and Salome, and that contributed to his death." I always kind of associated that with the song, although it would only make sense if John had given in. It'd be useful to read Wilde's play, as I'm sure Bono is familiar with it.
I remember reading somewhere that this song kind of fit with Mysterious Ways (like wowy, walk to the water, and luminous times) - with dancers and "Johnny" the baptist, can't recall if it was official or fan speculation. Of course taking Mysterious Ways in the light of John singing to Salome (wasn't he imprisoned, "living underground, eating from a can") casts an interesting light on things (as does the fact he was beheaded and "will she be there when you hit the ground, ow!" hehe).
re: the remix on the best of album it had <a href="http://www.u2wanderer.org/disco/songs.html">shown up earlier</a> - it just got an unannounced edit on the album. Not sure if it's all that important though.