I recently saw a demo that you may be interested in.

After, they mumbled a quick statement about the demo machine “its a dual 500!” as if no big deal. One of my friends attempted to correct him, but he let us know he hadn’t misspoken. He had a dual 500 MHz Ti PowerBook with 512 MB of RAM. We didn’t get too close, as it was only for demonstrations, but it was sitting on top of a cardboard box for the duration of the show, and when he put it away for the night, the box felt ready to catch fire!

More that I heard: it does have a redesigned motherboard, still uses PC 100 SO-DIMMs, shared the same case as the current TiBook and is hotter that hell.

Some thoughts about what is in store for the future of dual G4 PowerBooks: They should be released within the next 6-8 months, they will not use the current case, but instead a slightly colored one.