to retailers' specification data, Zotac's GTX 260 AMP! edition will end up working at 650MHz for the core. As you know, the safest way to go with GTX 280 is 670MHz and many AIB partners decided not to push those cards higher, but apparently GTX 260 might be a better overclocker.
The new Zotac GTX 260 AMP! card works at 650MHz for the core, 2,100MHz for 896MB of GDDR3 memory paired up with the 448-bit memory interface. It comes with 192 stream processors and a Shader clock set at 1,400MHz. These specs are close to those on the reference GTX 280 card, lower memory clock, but higher GPU and Shader clock. Of course, you must note that the GTX 260 has a 448-bit memory interface and 192 stream processors.
The retailer claims that this card will be available in one or two days time and it has the card listed for €379.90