This Friday the 13th, BioWare will take down the Star Wars: The Old Republic servers to perform unscheduled maintenance. During this window, servers will be offline but will return without the need to download a patch.
On Friday, July 13th, 2012 we will be bringing down the game servers and SWTOR.com for a brief maintenance period for two hours from 2AM CDT (12AM PDT/3AM EDT/8 AM BST/9AM CEST/5PM AEST) until 4AM CDT (2AM PDT/5AM EDT/10AM BST/11AM CEST/7PM AEST). All game servers and SWTOR.com will be offline during this period. This maintenance is expected to take no more than two hours, but could be extended.
For the thread announcement, head on over to the official forums.