I've got my Jetbook Color and I investigate about the sleep problem.
Gregg was right: the device goes in standby if you don't touch anything for about 4 seconds (infact the blue led near Menu botton turns off).
BUT (there is a "BUT") it works only when you are reading a document or viewing a picture. If for example you are on main menu and you leve your jetbook color on the table, you'll waste your battery's charge in about 12 hours!!!
I think this is a bug and as workaround you have consider a document as a standby button
Hope this help you
AM