So I was searching for new chunks on my small home server when I saw this:
Those lines aren't static either, they're spreading. Every few seconds a handful of water tiles turn a little bit darker. This is pulling a -lot- of resources from my server machine. It used to comfortably host 3-5 people over the LAN. Now if I happen to be in one of these areas the updates are happening I start hitching until I have to kill the client.
The map was created using the 1.1 server.(100% vanilla) I updated the server jar to 1.2.2, and the map happily converted itself. This is happening in old chunks as well as new.
Edit: Also notable, the sapling and apple in my hot bar were found decaying from "old-chunk" trees. All my big oaks are losing some of their outer leaves as if afflicted by some crazy tree-baldness. The jungle decay in new worlds seems to have been resolved... Though jungles still make my laptop whine in SSP. (Old laptop : First world problems)