Are you sure your files are all RAW and some are not jpeg?
My 450D has a RAW
bit depth of 14 and jpg depth of 8 bit (all jpgs are 8 bit). I right click & open raw files with CS3 and the DNG converter pops up with a box calling the image 16 bit.
I think when opening RAW files in photoshop it (the DNG converter) re-scales the bit depth to 16, see pic, with the dialogue box.
DSS and such like usually save files as
16bit Tiffs.
edit:
forgot the happy snap.