Mmm, I seem to have the same problem. Using 2 sidebars and both have lost widgets. Also lost recent posts and pics. Somehow there are millions of RSS feed buttons in my sidebars that I certainly did not put there. I hope the problems are solved soon.
A new fix is in place. Most blogs will have their widgets back now. If yours are not arranged as you like, you will have to rearrange them now. We apologize for that. The contents of individual widgets are unaffected.