Watermark'D v3.4 SS v4.7 <-------- LINK HERE!!!!
Stewart...can you check to see if your version of Watermark'd themes the Twitter app, version 1.0.3? I was able to apply the theme via update.zip, and it still hasn't themed it. No rush on the update...just wanted to give you the FYI if you update SS4.7 in the future.
*It showed it themed.
Here is an alt, I changed the name, only thing that changed...well, besides adding in another "different" Twitter.