Is it possible to have a laptop/desktop SLI? Haha....
I have seen a product from ASUS not far back where they had a mobile GPUthat you could connect to a lapton..... Its true but i think it only used an 8x connection
It's not setup for true Xfire, but it's somewhat hybrid.
ATi and their vendors also have external solutions for testing that use multi lanes to external board to simply test engineering samples, they are similar to the 2 x 8X connectors on the LASSO solution.