A report at Fudzilla mentions that the Radeon HD 7990 GPU is codenamed Malta, and not what we were previously led to believe, New Zealand. Moreover, the the card could feature dual Tahiti XT cores that may run above 1 GHz, which might leave Asus somewhat concerned. Asus's fastest card on the market at the moment is its ARES II card, which is a Dual 7970 card that has its own liquid cooling loop. Asus's card is clocked at 1050 base and 1150 Boost, but the reports indicate that AMD might be looking to exceed these speeds with the Malta GPU.
Other information is that the card will come packed with a massive 6 GB of GDDR5 memory (unsurprising seen as the 7970 carries 3 GB) along a 2 x 384-bit memory interface.
Sources also indicate that the card would launch within a few months from now, but some of Fudzilla's other sources claim that the card is around the corner. It is fair to assume that AMD is waiting for the real world tests of Nvidia's new GeForce GTX Titan, and then clock and price its 7990 accordingly.
Unfortunately that's all the information we have for the time being, but it's good to see that AMD is living up to its promise of delivering more HD 7000 goodness this year.