The following is from OCLC.
All services unavailable 3 January 2015 for technology upgrade
On Saturday, 3 January 2015, OCLC has scheduled a technology upgrade to support system performance and reliability. During this upgrade, all OCLC services will be unavailable on 3 January 2015, from 12:01 am to 3:00 pm, U.S. Eastern Standard Time (approximately 15 hours).
We will notify members as services come back online following this upgrade; real-time System Alerts will be posted to the OCLC Support website throughout the day. Please contact our Customer Support team should you have any questions prior to the migration.
While we scheduled this maintenance event to occur during a slower time for many of our member libraries, we understand that this event still impacts many. We apologize in advance for any disruption to you and your users.Thank you for your support. We are committed to the ongoing enhancement of our systems, infrastructure and processes, and will continue to advance our delivery to you.