You might look at the topic under this heading - Arduino as Stepper Controller. http://arduino.cc/forum/index.php/topic,84809.0.html
Can do Full Step, Wave Step and Half Step.
Without optimizing it will accept Step pulses at greate than 1000 steps per second. (I have tested it to 146 RPM ) The speed limit for now is the fact that my pulse source is only capable of going that fast at the present time. If I change the clock on the ATtiny2313 I should be able to double that with nothing else required. If I can get my assembly code to work it should be able to go faster than the motor.