This E-0 stepping Nocona supports an 800MHz FSB (front-side bus), 64-bit extensions in the form of Intel’s EM64T (Extended Memory 64 Technology), and Intel’s Execute Disable Bit (EDB) security technology.Source: DigiTimes
The rollout of the E-0 stepping part was delayed due to a minor change Intel was making in the specifications of the chip, according to the sources.
According to Intel in Taiwan, the Nocona E-0 stepping part is already available to select customers
Intel to ship Nocona processors with E-0 stepping on October 29

Intel informed clients that Nocona processors with the new E-0 stepping will be availble on October 29. Processors with this new stepping were previously expected to be available at the end of Q3 2004.