This would be a nice upgrade path for me on my laptop.
I have two HDD bays and an mSATA slot in my Dell Precision and one bay has an m4 128GB SSD. So assuming equivalent pricing I can get a 128GB mSATA to upgrade instead of going all out on a 256GB SSD to replace my current m4.
ikefu: Don't waste your money on the 128GB. It will run out of space really quickly, and the performance of SSD drives declines severely when they are running low on space.