the lucid chip will make 2 different cards work together for apps that it's programmed to work with which includes many major games, but it wont work like simple math, there will be a performance increase but not as much as the indervidual hardware stats say up if you added each's perfomance stats together, because it will suffer, maby between 20-80%, depends what cards and mainly the programming of the lucid chip.
So you might run a GTX 560 with HD 6870 maby or GTX 560 with GTX 560Ti or GTX 580, depends on if the lucid chip can accommodate that setup, I last read about it with last phase GPUs like GTX 4XX and HD 5XXX. Maby it's still going for todays market.
Because the boards with Lucid chips are very pricey and the performance often doesn't add up, it's a complicated way to fix a budget problem I think, like if someone doesn't wait to get the proper SLI or X-fire job and tries to keep an old card in the mix. Maby there's some advantages for it though it's mainly aimed at gaming and you'll only get the best from the source, this Lucid is sketchy too, after-market stuff me thinks