Some features and images are floating around the Internet concerning the Athlon 64 4200+. Apparently, AMD is close to releasing this CPU.
This CPU is actually clocked at 2600MHz just the same as the FX55 but in the case of Athlon 64 4200+ the multiplier is locked higher. The 4200+ has 1MB of cache built on 90 nanometre marchitecture and works with 1.4 volts.
The Inquirer describes the CPU as being "a San Diego core... [that] has SSE3 and it is built on 90 nanometre marchitecture."