Opteron is the AMD processor targeted to the server market. It is also based on the Athlon 64 architecture (a.k.a. x86-64 or "hammer") like almost all other CPUs from AMD available on the market today, like Athlon 64, Athlon 64 FX, Athlon 64 X2, Turion 64 and Sempron (socket 462 Sempron models aren't based on this architecture, however). In this tutorial we will present Opteron's main features and also several tables listing all models released to date.
You can check it out over at Hardware Secrets.