Clawhammer is/was the codename for the first
64-bit AMD processor. Clawhammer will (was to be?) be aimed at the
desktop and low-end server market, while the more powerful
sledgehammer will target the high-end
SMP server market. The first clawhammers were expected to hit the market in the first quarter of
2002, however, nothing resembling clawhammer has shipped yet (as of March, 2003). As far as I can tell, the "clawhammer" and "sledgehammer" codenames have been dropped by AMD, as no articles published since early 2002 mention them.
See also:
Sledgehammer,
IA-64,
Itanium