Apparently, way back in 1999 AMD filed a patent which gives them rights to release a processor with hyper-threading technology. Entitled "Microprocessor configured to execute multiple threads including interrupt service routines", the patent outlines how a CPU can execute multiple threads concurrently.
So, its not outwith the bounds of possibility that we could see an hyper-threading enabled Athlon64 processor in the works for some time in 2003. Certainly, for AMD to remain as competitive with Intel as possible, it would be a smart move.
More here and The Inquirer.