Found the reason for the postponement. didn't see it posted, so here you go.
"FINAL FANTASY XIV Open Beta Test Postponed: Follow-up
We would like to take this opportunity to provide an update regarding the FINAL FANTASY XIV Open Beta Test, which was announced to be postponed on Aug. 31, 2010.
A critical issue where the client software for the open beta test would not respond on certain rare occasions has been addressed. As of now, we are in the final stages of preparation for the start of the FINAL FANTASY XIV Open Beta Test.
A new schedule will be released at a later date. Until then, we ask for your patience in this matter." --- PSN: RX--Zero "Humans are greedy, therefore they are human."