So I fired up Minecraft this morning, and it patched to beta 1.0. Lovely. Broke my mods, as I expected.
Had to go to work though.
Get home, fix up my mods as best I can, fire up Minecraft again. It patches itself again. "Notch done fixed up that chest bug" I thought to myself. Get to the main menu, and the version has reverted to Alpha 1.2.6