This is my busted Thomson Elite seatpost. It was a lovely piece of equipment while it lasted. Broken while sitting down right after powering up a steep little hill in my final race of the year in the excellent Mud, Sweat, & Gears cyclocross series. No DNF for me... I rode 2.5 laps for ~30 minutes standing up with my seat dangling around on one bolt! The other bolt was attached to the broken off piece when it cracked but got jiggled loose while riding. I had to walk the course to find that seatpost piece but the bolt was not to be found in the nearby mud and grass.

Data on outside of seatpost:

THOMSON
SP-E102
27.2X250
28151
MADE IN USA

Sticker on inside of seatpost:

CHKD4
QD100

UPDATE: The fine folks at Thomson replaced my seatpost! Apparently it was an older model and if the bolts were over-tightened and left that way for a long period of time (years) then such failures can happen. This may have been the case with my post but I don't know for sure. Apparently this type of failure is unlikely to happen if you use the proper torque. New post mounted with a torque wrench so should last a long time. Again, thanks Thomson!