Besides the smaller 34nm flashchips Intel has a new controllerchip and there is more DRAM cache available as well. In a number of benchmarks the new X25-M performs even better than the SLC based X25-E drive with 35GB storage.
The new Postville X25-M is upped from a 16 MB Samsung 166 MHz memory chip to a 32MB version from Micron. The extra cache means the drive can process more small random writes, which of course is incredibly awesome, since that's what it's about!