This has happened a few times over the years. This is to keep the version numbers in the proper order, even when an older OS received an update after a major new release came out. Some entries may appear out of chronological order (i.e. Note: The Days column reflects the number of days between releases.
Ⓘ Leopard - First universal binary release Ⓘ Snow Leopard - First Intel-only release
Ⓘ Lion - App Store only (USB stick later) Fixes a launch issue for certain 32-bit apps * This release is not included anywhere on Apple's site.
