Hmmm, Metropolitaines is most definitely the Official Paris Metro Font (TM) and there are indeed many entrances to Metro stations in Paris decorated with signs set in this face or something very similar.

However, it would seem that the font on Brad's picture is actually completely different and devoid of obvious Art Nouveau stylistics.

No idea what it is though, I don't expect it's available in digitized form. Then again, it shouldn't be too hard to recreate this from scratch (especially if all you wanted was a sign saying [METRO])...

Well, as designer of Parisine,* the official signage typeface of the M�tro in Paris, I can inform you that the company asked a young designer (David Poullard) to design a new face based on old Guimard signs in 1999. The font is called "M�tropolitaine" (note there is no s) who include several ligatures and such things. Its a beautiful but exclusive typeface.

No online samples available. But you can see it on a book published by Muriel Paris in France called "Des caract�res" in 2002. To contact here: See this page: http://www.typofonderie.com/Gazette/PTFManuelParis.html

(*http://www.typofonderie.com/Gazette/PTFParisine.html)