The time surface of the Heartbleed attack is a lot smaller than what most think. Debian and the BSD projects moved to v1.0.1 earliest, around March/April last year.
Ubuntu only upgraded two months ago (in 12.04.4) on the 6th of Feb:
http://fridge.ubuntu.com/2014/02/06/ubuntu-12-04-4-lts-relea...
Redhat with 6.5 in November 2013:
https://access.redhat.com/site/documentation/en-US/Red_Hat_E...
CentOS Feb 26th 2014: