Everyone watching this thread, please submit a Better Business Bureau report (bbb.org), just as I have.  Report that you have contacted AT&T to inquire about the updates MS has made available to carriers to address significant issues (one is a security vulnerability, the other is the disappearing keyboard issue) that are addressed in the update AT&T refuses to release.  You should be contacted by AT&T.  I just submitted mine tonight, so I'm not expecting any reply until next week (or within 15 business days.)  If everyone did this, and by everyone I also mean those that are not posting in this forum and are simply reading it, maybe this will put significant pressure on AT&T to do the right thing (release the update.)