Sadly Sony has confirmed on its forums that on July 26th will have a maintenance period for PSN will indeed affect North America as well as other territories.
Sony says that "In order to continue to deliver you the best online games experience, we will be performing maintenance on the network this Thursday, July 26th. This maintenance will start at approximately 8:00 am PDT (9:00am MDT / 10:00am CDT /11:00 am EDT) and end around 11:00pm PDT on Thursday, July 26th (1:00am MDT / 2:00am CDT / 3:00am EDT on Friday, July 27th)."
The same can be said for Europe, coming from the European PlayStation Blog, the PlayStation Network is set for “scheduled maintenance” that will occur beginning on Thursday, July 26th.
Times for Europe (BST) are 4pm Thursday afternoon through 8am Friday morning.
However, Sony does mention “if you wish to play online during the maintenance, then you may be able to do so if you sign into the PSN before the start of the maintenance window.” So in case you want to play PSN you should leave your PS3 on and signed on.