I recently watched Direwolf20's video on IC2 1.65, and I began thinking a bit about version numbers. Going from 1.63 to 1.64 was a minor change; some bugfixes and a single new item. Going from 1.64 to 1.65 appears to be a major change, adding a great amount of buildcraft compatibility, four new redstone behaviors for storage devices, and a really nifty new ability for CF Foam. And with minecraft -- going from 1.0 to 1.1 added some minor features -- bow enchangments, sheep regrowing wool, no ladder collision boxes, etc. (What does removing the ladder collision box actually do anyway?) But if the snapshots are any indication, the 1.1 to 1.2 update will be quite major -- for starters, the entirety of the ai code has been rewritten.
That's pretty much it. Any more thoughts?