I know a lot of you are headed to WDW soon so I thought you might want to see some great pics of the moat drained:
There are more at:
http://www.wdwmagic.com/Attractions/Cinderella-Castle/News/15Jan2010-Cinderella-Castle-moat-(and-beyond)-draining-photo-update.htm
Got it off DisMarks if you want to vote for it:
Cinderella Castle Draining Moat Photos
Wow! Is that sediment at the bottom or just wet pavement?
May 2008 CSR 
When we were there last two weeks they actually had a Bobcat front end loader down in the moat with a crew that had high pressure hoses and were washing the moat and hauling it away. I was surprised to see them doing it in the daytime hours.
You never know what they're going to show and not show. Sometimes, refurb and demo is wrapped up tight. Sometimes it's all out there in the open.
Must have been cool to see!
May 2008 CSR