There is an eCS 1.2 Athlon64 beta 2 available on the eCS BetaZone. This utilizes IBM's recent kernel updates, which fixes crashes on Athlon64 (and Pentium4) systems with more than 512MB of RAM, as well as the latest DaniS506, which provides support for many SATA chipsets. It does NOT utilize any of the 64-bit features of the CPU.
http://www.ecomstation.com/...
Source: OS/2 Warp News and Rumors