FOOK2 for FO3 had a Taurus snub nose revolver. You'll probably find quite a few others if you do a search on FO3Nexus, too.
I own a Smith and Wesson Model 36. It's a 5 round .357 Magnum revolver with a 1.75 inch barrel. It's not much bigger than my fist.
Probably the main reasons you don't see as many snub noses added to the game as you do, say, for example, Barettas, or Glocks, is because revolvers don't fit the typical "gangsta" mentality, and because of the inherent accuracy issues of a gun with such a short barrel.
At < 30 feet, I can put all five rounds in to a group about the size of a coffee can. If I step back five feet, I'm lucky if I can get two or three shots on a 8.5"X11" sheet of paper.
In other words, a snub nose is functionally useless at more than about 30 feet.
A modder has the choice of making a snub nose pretty accurate regardless of the range, or making it so you miss your target 75% of the time regardless of the range. I don't think the Spread setting on a weapon allows for enough flexibility to be able to realisticly emulate the accuracy of a snub nose.