I am 100% with Mike on this whole discussion. There is, in my opinion, no valid technical reason to ever warrant rearward facing dropouts in any even remotely commonplace application. Many posters have mentioned the rearward facing dropouts offering the possibility to make a bike with shorter stays, but any experienced mechanic/framebuilder will confirm that this is simply not true.
With super-short chainstays and a fixed gear application, you must always still leave enough room in front of the desired wheel fixation point for the wheel to be moved forward to allow the chain to be removed. If you did not leave the space, you would instead need to remove the chain by removing a chain link which is hugely more complicated than deflating the tire; ergo, you cannot make shorter stays. If instead, you are using a derailleur, a vertical dropout is the way to go to have ultrashort chainstays.
The only case where a rearward facing dropout could eventually be useful is in the virtuallt unheard of case of bikes where the the seattube(s) are set up in such a way that rear wheel becomes ensconced within. This example does occur in the case of some bikes with the rear wheel coming to be installed between dual seattubes, or within an aerodynamically formed seattube cowl. However neither of these applications could ever be considered commonplace, nor are they approved for typical sporting events.
The only advantage I see regarding the "track" dropouts is relative to their heft, not the direction of their opening. As mentioned by Mike, anybody intending to take advantage of the length of dropouts is far better off to make them forward facing.
Steven Maasland
Moorestown, NJ
USA