Yesterday I had a chat with Mike Sterling from the Hyper-V product team at Tech Ed 2008. And guess what? When I told him about my issue with direct attached disks larger than 2 TB, he told me this will be fixed in the next publicly available version of Hyper-V. He would not comment on the time frame or when it is supposed to be available.
At least the keynote mentioned that Hyper-V will release before its current deadline in August.