Whoops! You're right. I had thought I read somewhere the brain requires another organ to convert ketone bodies to glucose, but it appears its the liver itself at cannot use ketone bodies:

http://en.wikipedia.org/wiki/Ketone_bodies#Uses_in_the_heart...

Yeah, the liver has a separate metabolic pathway for converting non-carbohydrate organic compounds into glucose at a steady rate to regulate blood sugar and provide energy to the brain, it's called gluconeogenesis http://en.wikipedia.org/wiki/Gluconeogenesis