The ETI-1 supports annotation, this is a color device that is being used by the
USAF
This does not look to be commercially available but from the specs looks pretty interesting. I wonder if it lives up to it's 8 hour battery life. I am sure that it is prohibitively expensive and seems hobbled by proprietary restrictions.
Oh, and just for giggles I have checked out the forums for the eFlybook, they are just as frustrated with the iLiad there as we are, and they paid a lot more!