Hi Brian
Now about that 909; Actually it was the last hurrah for the full size 3900 series. S&W had just released it's "value series" which were nothing more than 3rd Gen. Smiths without all the bells and whistles (i.e. no ambi safties, dull blue finish, no Novak sites etc.) but they were still the same old reliable Smiths we all come to appreciate!
The 909 is a full size 9 shot double action first shot(single action afterwards) 9mm pistol. The reason it came about; well the Clinton hi cap magazine ban was still in effect.
There was a smaller version called the 908 that is the same size as a 3913. The 909 is the same size as a model 39 or 3904.
Also there was some talk that they had simplified the locking lugs on the barrel of the 9 mms but the .40 and .45 versions still used the Browning system. Hope this helps! Dale