So I was trying out the 1.23 RC client, with shadows enabled. I set the time to midnight, and was a little disappointed; I had a faint shadow as if from moonlight, while the much closer and brighter lantern didn't cast a shadow.
I looked off to the west at the Sun Gate just offshore.. and was amazed to see that the moon was positively huge! I took a snapshot... hmm, I don't see the moon in the preview, but I'll save it anyway... Later, I opened it up under GIMP, and it was solid black!
To show I wasn't just seeing things [um, wasn't that just what you were doing? --Ed], here are screen captures:
It's a neat effect, but... I've made a JIRA entry for it.
Now, I did have Compiz Fusion turned on. I will try with it off, and see whether that makes a difference. (BTW, that video is almost two years old. It's even better now.)