Square Enix have posted up a notice on the beta site saying that the open beta has been postponed from the initially announced August 31, 1900 hours PDT, which I assume is September, 1400 GMT. Darn these time zones.

The postpone is "due to a confirmation of critical bugs" and a new schedule will be announced at a later date.

Here is the notice,

FINAL FANTASY XIV Open Beta Test Postponed

FINAL FANTASY XIV Open Beta Test, which is scheduled to begin at 19:00 (PDT) on Aug. 31, 2010, will be postponed due to a confirmation of critical bugs. New schedule will be releaseｄ at a later date.

Along with the postponement of FINAL FANTASY XIV Open Beta Test, the issuing of registration code for FINAL FANTASY XIV Open Beta Test will be postponed as well. With the download of client software's installer, it will be suspended at 19:00 (PDT) on Aug. 31, 2010.

We apologize for any inconvenience this may cause.