So, about a month ago I began working on my current world. It was pretty nice and all.
Anyway, I had basically converted this entire mountain into a base, with a train and everything. Even a giant tower.
Now, I updated Minecraft today, and "converted" the world to the new format like all the old worlds had too. My world already used MCRegion, so I guess there shouldn't have been much change. It didn't take long anyway.
I went back to 1.2_02 since that world had mods installed on it, and the mods weren't updated to the latest version, and when I got on it..
That's exactly how it looked a month ago when I first generated the world (except for the extra flowers, I didn't even make that mod until a while after I generated the world). I still have my items in my inventory though.
So, yeah. Cool, I know, a month of work just got wasted because of an update. :biggrin.gif: