I accidentally hit "Yes" after my java crashed and I had to relog.

Does anyone know any downgrade links to a 1.2.3 jar?

As wawon0 put it, this is a small update with most of the changes client-side. Few if any plugins should break, which means that the only thing we have to wait on this time is a stable server build. Much of the 1.2.3 update was waiting for critical plugins to update.