I think that 2nd gen Raspberry PI should use:
- Single/Dual Core ARM Cortex A7 CPU at least 700mhz
- 512MB RAM
- Lower power usage (from 2 to 3 watts down to 1 to 2 watts)
For a $25 computer the 24GFLOPS GPU might be powerful enough to play most games that can be played on ARM computers right now expect ailen-arena.