|Sony Alpha 500mm f/4 G SAL500F4G Lens (image: www.ephotozine.com)|
At CES 2012 Sony displayed a chrome 500 mm F/4 G lens, that's currently in development. The SAL500F4G. << UPDATE: You can buy it now from B&H for $12,999.99 >>
I also see it being called a Nikon lens on several sites and forums, but it's actually a Sony G-Lens.
Sony - SAL500F4G 500mm Lens - CES 2012: