Update: Read the comments for instructions on how to enable a lower-quality (but working) digital viewfinder…
The MCA-25 does partially work. The digital preview does show black, but if you take the picture it will save to the camera’s internal memory (try deleting any pictures on the camera before-hand).
From there, go to view pictures (in the CommuniCam menu), select the picture, press the Preferences/Menu key, and chose Copy To Phone. From there you should be able to view and assign the picture, as well as send it via Bluetooth.
That doesn’t mean the T608 now works perfectly with the T608, Sprint needs to request a bug fix for this problem to SonyEricsson. Note to Sprint: You sent T608 firmware cables to stores for a reason, you spent the money on them, now do the right thing.