How to detect SSD in Mac OS X?

Question

Is there a reliable, quick, deterministic way (i.e. not a benchmark) to check whether the system drive Mac OS X is on is a Solid State Drive?

Is there any other

Answer 1

The number of threads? 1 is going to overwhelm any disk, SSD, RAID or not. Disk is slow, processor is fast. The OS is going to reorder your disk requests anyhow (or at least it should) to get the least head movements.