-UPDATED-
Greets,
The update will be deployed at 12 noon EDT / 4pm GMT and will require a short downtime. We were not expecting a downtime for this update as it is a client-side update. However, we decided a 15 to 30 minute downtime would be needed in order to ensure everyone online will patch and log back in. As mentioned above, the downtime is only expected to last 15 to 30 minutes.
To find out what this is in your timezone please check here.
Happy Hunting!