I have completed the required maintenance on ODK's servers. Build and Xls2xform should be back up and running.
There were a handful forms that appeared to be corrupted when I ran my database update script today. I would venture to guess that they're rather old, as I fixed a bug many months ago that could have caused that issue. I cleared some metadata on them, and they should still function, though you may have to re-add some of your languages or resave your bulk select/select1 options in these cases. They should be rare.
Please let me know on the mailing list if you see any new issues, particularly with forms not loading or with login failing.