I've been reading some more about this card on tom's hardware. The reviewer wasn't allowed to give figures yet due to embargo rules, but it doesn't look promising. He made comments about how the card is good "for its size" and that it only makes sense if you want to build a smaller form-factor PC with good GPU performance, or, if you have a boat load of cash to buy 2 or even 3 of these.
So from what I'm deducing the card is:
Very fast for its size
Scales really, really well when paired with more of them.
However, it's not going to be faster than a GTX690 (yes, it's a dual GPU card I know) which is a lot cheaper than this new Titan. So the GTX Titan seems to be a VERY expensive "new toy", which can be outperformed by cheaper products that are already available.
The 6GB memory does seem amazing though.