We already knew the GeForce 8800 GT wouldn't support it but what's new is that the new G92-based GeForce 8800 GTS won't support it either.
We saw the first pictures of the reference boards at the tail end of last week, and now OCW has quite rightly pointed out that, without the dual slot connector, there will be no hot 3-way action for the GTS.
Whilst Nvidia reckons that Tri-SLI can be achieved over the PCI-E bus, that's going to be a slow and buggy solution for the foreseeable future.
In the short term, at least, it seems that 3-way is going to be restricted to the 8800 GTX and Ultra. Can you imagine the mortgage required for three Ultra cards? We'd rather not.