PayPal will be down for approx. two hours on May 24th, from their latest update on the subject:
Please note that the starting time of this scheduled maintenance will be May 24, 11:00 PM PDT (May 25, 7:00 AM GMT) and ending time will be May 25, 1:00 PM PDT (May 25, 9:00 AM GMT). Total time of the activity will be 2 hours. The planned service interruption will be between May 24, 11:00 PM PDT (May 24, 7:00 AM GMT) and May 24, 11:45 PM PDT (May 25, 7:45 AM GMT).