I just downloaded the latest Windows nightly, and it had the string r7923 embedded in the executable, suggesting that the code DrSuperGood posted (or some alternative) is run. I didn't try running the nightly, though, since I didn't want to mess up my current installation, so it may be that this isn't shown in the caption bar anymore for all I know.
The revision number is however not shown when looking at the file details in Explorer. Does anyone look there at all?