It's real and the guys at Fudzilla have confirmed that the Nvidia Geforce GTX 590 was shown running at CEBIT 2011. According to them, The card is real, It is quiet (Less Noise from the fans) and it's coming real soon. Also the card alone is enough to run Crysis 2 in 3D at a very nice frame rate. The rival card from AMD "HD6990" was also seen at Cebit which you can see here.
The card comes with 2 x 8 pin power connectors but still it runs hot which isn't a surprise for a card that's based on dual GF-110 chips. The design of the card was also different then the one EVGA showcased on CES 2011 event, That would be because the new card is based on the Reference design while the one EVGA showed was a Custom Edition of the GPU.
Chances for a release in March Q1 2011 are high but still aren't confirmed, The clock speeds are yet to be finalized as Nvidia is waiting for release of the AMD's HD6990 and then it would decide the final clocks of its next flagship GPU. As soon as more info pops up we'll be sure to let you know about it. 😉