UPDATE: The source looked at the picture wrong, I apologise if I got some people excited! The GTX590 will be a dual-slot card, at 297mm in length which is close to the GTX295's length.
The launch of the soon-to-be amazing GeForce GTX 590 dual-Fermi based GPU is about to go live and the closer we get to the release, the more that leaks out about it. NVIDIA has obviously put a lot of green sweat into this puppy and the latest shots show a 21.5mm-thick cooler which would imply that it's a single-slot based cooler.
This would be an amazing achievement if true, but could also come at the cost of your ears. If it is indeed true, NVIDIA have pulled a rabbit from the hat and should get some fairly good press based on the cooler design alone.
Below is a shot of Sparkles upcoming single-slot GeForce GTX570 which was shown off at CeBit, looks quite sexy as a slimmed card.