The guys at OCWorkbench posted a few pictures of what is meant to be a Radeon HD 2600XT. Apparently the Chinese website PCinLife posted these pictures and leaked some specifications.
According to the author at PCinLife, the board uses 256MB of GDDR4, 65nm manufacturing process and a bios dated April 4th. Maximal Wattage is 80W or lower, since the card doesn't need an additional power connector, unlike the Nvidia 8600GTS. In one of the 1080p video test, cpu usage was lower than 5% on average which is a great score. This does sound promissing.
Here are some of the leaked pictures thanks to OCWorkbench.