It seems that the AI was at least twice updated without this being noted in the patch notes. First major thing that i saw was a much better defense against a cannon rush. Then patch 1.1.2 went live and I played a few games against hard AI to test the changes. I was very surprised to see that the second attack wave from my protoss enemy (i was zerg) came with 1,1,1 upgrades. I think before the patch even Very Hard AIs did not upgrade armor/weapons/shields at all (or at least not so soon).
Is it just me or did someone else notice this? Why is blizzard doing this and NOT mentioning it in patch notes? I can understand why they wanted to update the AI, but why not mention it?