XFX is working on an overclocked edition of the Radeon HD 5970 Eyefinity 6. The clockspeeds haven't been finalized yet, but it will likely be 850MHz for the GPUs and 4800MHz for the 4GB GDDR5 memory. The card has six mini-DisplayPort connectors and will feature a custom cooling solution (which is still under development).
This custom card will be named XFX HD 5970 Black Edition Limited and the launch is expected by the end of the month. Only 1,000 to 1,500 cards will be made, but they will be sold for around $1,000 each.