Erm, you've got that a bit mixed up. Arm don't make any processors at all - they licence the core, provide applications support and that sort of thing. They're an IP company, and a very successful one at that.

The StrongARM is one implementation - originally designed by Digital before Intel bought their processor business. Another implementation example would be the Cirrus 7212 as found inside the Rio Receiver (at 75Mhz).

I haven't a clue where you came up with 57Mhz - the clock rate is an implementation issue. There are dozens of licencees building ARM based silicon. The code is broadly compatible on all ARM implementations, with individual versions having a few unique features here and there. The instruction set is tiny - a truly orthogonal RISC architecture.

Rob