An interesting three-year look at the DSLR market showing share, and change, since 2006, from the German online magazine PhotoScala, link here. 
 

Note from the site-  any "system camera", or, as they describe, a camera with interchangeable lenses, is included- thus, the mico 4/3, Leica...
 

Bottom line- Nikon has been gaining a bit of share, at 33/47 in '06, 40/42 in '07 and 37/38 in '08 (Nikon/Canon) and the Sony/Olympus split has gone from 6/6 to a dramatic 13/5 share putting Sony in a remote third place.  Panasonic has gone from the "All Others" category of less than 1% to holding it's own 2% in '08.  Fuji, Leica and Sigma, etc, represent 1% in '08. 
 

We can't speak to the accuracy of the numbers, honestly I'm not even sure if they're talking units or sales, (they mention both "sales volume" and units) but nevertheless, interesting...