Hmmm.... sector still had random data after rm tmpfile and sync;
/dev/sda3 on / type ext4 (rw,noatime,nodiratime,discard)
Device Model: KINGSTON SS100S216G Serial Number: 16GB40013421 Firmware Version: D100719
Suppose to support TRIM.
Just so you know, in Jan '09 there was a thread on the linux raid list where they discussed the TRIM command on SSD's. The gist of the conversation (as I understood it) was that for SATA based SSD's, the results of a raw read afterward were non-deterministic, ie you couldn't be certain what you'd get back.