My guess:

Patch 3.3 - ICC - Dec 2009
Patch 3.31 to 3.5 - Bug Fixes for ICC - Jan/Feb 2010
Patch 3.9 - ICC dumbed down - Mar/Apr 2010
Patch 4.0 to 4.2 - Cataclysm World Events - Aug to Oct 2010
Cataclysm - Nov 2010