We just got this notification from Serials Solutions (the provider of our Summon discovery interface).
Note that library searching in MIDCAT will not be affected.

“Downtime Notification for
March 24, 2012
Due to extenuating circumstances, Serials Solutions services will be unavailable to you and your patrons on Saturday, March 24, 2012, starting at 8:00 p.m. EDT in order to implement an emergency upgrade. The service outage will be no more than one hour.
We apologize for any inconvenience this may cause you and your patrons.”