CraftHub has been kind enough to upload the old client and have allowed us to link it to you and your players. Since we are not updating until tomorrow given the state of the beta release, we would suggest you use this to play until then.
Feel free to link your players here to download as well. You must replace minecarft.jar in your .minecraft folder with this one.
https://crafthub.s3.amazonaws.com/minecraft.jar
Monday, December 20, 2010