The Sony DSC-T7 is just as thin as the Casio S600. The Pentax Optio S6 is a tenth of an inch thicker, but is also smaller overall. The Fuji Finepix Z1, Nikon Collpix S3 and Konica Minolta DiMage X1 are also close.
The Panisonic DMC-FX7 is a bit larger, at about an inch thick, but also has optical image stabilization and can currently be purchased for near $200 (It's $230 at Radio Shack!).