The product looks really promising. Because the TiBook has some heat problems under OS 9, this might avert turning on the fan quite as often.
Even though I'd like to see one of these installed on my TiBook at one time or another just to try it, I don't think it would be a great addition for those who put their notebooks in carrying cases. It extends the rear of the notebook by a few inches.
The TiBook is already oversize as it is. I don't think I want mine any bigger than it is already, otherwise my carring cases will definitely not fit it.