Aye, use MCNostalgia. It downgrades your Minecraft.jar to an earlier version, going back as far as most could possibly want. The link above for downloading the jar files is quite illegal, so ignore it. However, should you Force-Update, it will probably update to 1.1... although one can't be certain, since Minecraft generates hashes and may overlook the fact you redownloaded an older version, since the hashes are saved to a file. It's possible it won't ask you to update until Jens releases 1.2.