Past OS X Releases
--------------------------------
10.0 (Cheetah), last release 10.0.4 (?)
10.1 (Puma), last release 10.1.5
10.2 (Jaguar), last release 10.2.8
10.3 (Panther), last release 10.3.9

Current OS X Release
-----------------------------------
10.4 (Tiger), (as of May 2006, last release is 10.4.6)

Announced OS X Release
-----------------------------------------
10.5 (Leopard)

============================

More details at en.wikipedia.org/wiki/Mac_OS_X