Sapphire announced at the CES recently that they plan to soon start shipping one of the first Dual-GPU Radeons, based off the X1950. Lacking DirectX 10 support, it largely will not be well received with Windows Vista, and newer games will probably not support it well. That aside, for a first card it has everything needed to offer excellent performance, and supposedly will not be terribly expensive.
With the 8800 series cards already on the market, I question as to why they would push a non-DX10 compliant dual GPU card this late in the game. Regardless, it's interesting.