TrueCrypt suggesting migration to BitLocker?
In order of likelihood:    * Defaced site, timed to screw up a big announcement
    * Rogue content maintainer
    * Phase II of audit turned up something rather bad
      (edit: NO - see tptacek below)

edit: Variations on "developer forced to do this" (cf simmerian's comment):    * Developer was big brother all along and they are shutting it down
    * Security vuln about to be disclosed, dev scrambles to inform (albeit poorly)
    * Legally or otherwise compelled to compromise source code,
      dev complies and/or nukes project from orbit

The last alternative would be suggested in part by the strange content of the page, assuming it is legit from the developer: Normally I'd expect at least something like "there's a major vuln that is unfixable and we'll disclose formally in a week/two, migrate now.".