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No one knows for sure, since it is still quite some time in the future. AMD could always hit a snag and have to delay things a bit more. AMD is basically putting all their eggs in this one basket - and at the same time trying to impress the server market (which would require a very stable and mature chip). Thus AMD must have this chip perfect at its launch. A failure here and AMD's reputation will probably be ruined forever in the server market. For that reason, AMD will keep delaying it until all kinks have been worked out.
AMD's official stance on their roadmaps is that both will be out in the first half of 2003. That could be anywhere from January to June. Realistically expectations are roughly April for the workstation Opteron (Sledgehammer) and May/June for the desktop Athlon 64 (Clawhammer). One question that hasn't been answered yet is will AMD release it before people can buy it? The last 4 top desktop chips from AMD were announced an average of 6 weeks before you can see them listed in stock on online stores. If AMD does that with Hammer, then you'd have to expect a May/June Opteron and a July Athlon 64.