Good eye! Yep, the Blackburn Flea 2.0. Battery life isn't great, typically I get a couple days between charges, in deep cold I charge it daily. The Flea is a good secondary/safety light, and it mounts directly to my Bell Muni helmet (simple & easy). My primary light is a NiteRider 700.

edit - forgot to post: no ride today, it's snowboard coach night. I'd rather bike on these brutal cold days (-10F) than snowboard; you just don't work up as much body heat snowboarding. Oh well, the hill will be very quiet on a sub-zero day, no lift lines.