JCWR - The A9 appears to be a logical progression of a Unipod (or vice versa, the Unipod being a spin-off from the A9, I don't know). Given how many peripherals were mounted on the Unipod - both in terms of what was used and what wasn't, I would imagine that the board sizes are not dissimilar.
As to making it a laptop; I would imagine getting the components (cases being a well-known sticking point!) and sufficient market size to produce a laptop will probably be more prohibitive than the act of making one.
If an OEM were to order such a thing in sufficient quantities, then I suspect anything is possible; I would doubt that the RISC OS enthusiast market would draw sufficient numbers to be able to obtain the components :o(. Personally, given my current needs for a laptop, I'd have to agree I'd be on the front row for one .