Executives who want them are entranced by the form factor, yet find a less optimum experience when actually trying to write on the things. When you're used to writing in such a manner that your wrist is flat on the surface of a desk, it's difficult to get used to writing on a raised platform. Sort of like trying to do any sort of fast typing on on-screen video keyboard.
P.S. I have no experience with Forrester and their predictions, but as far as ratios of notebooks to workstations go, right now they're mirroring Gartner's projections which IIRC, has the ratio at 80/20 in favour of laptops by 2012. Anyway, that number came up at a tech conference but I was unable to get a source for it, so take it with a grain of salt for now. (You have to *pay* for Gartner's research and I'm just not that flush - or interested - right now)
