The green sidebar on the right is set to 100% height of the #contentbody but the sidebar keeps coming up short.
I tried to model the layout after http://www.alistapart.com which has the sidebar done correctly - I just can't seem to get mine to work.
SideBar height set to 100% - but doesn't work
There was just a great AListApart.com article by Dan Cederholm that talked about a technique for simulating what you are talking about:
Maybe this will help you achieve the effect you're going for.