updated 07:10 pm EDT, Fri April 19, 2013
All issues now cleared, but service interruptions a hassle for many
Apple has reported some brief but widespread slowdowns and unavailability of Game Center -- starting in the wee hours of Thursday and again later that morning -- coupled with a prolonged mail issue that only affected a fraction of one percent of users on iCloud.com for half a day over Thursday and Friday. The disruption comes on the heels of scattered reports of brief iTunes Store outages and a more serious iMessage and FaceTime problem ten days ago, the latter of which lasted over five hours. All services are back to normal operation now.
The email issue would have been completely unnoticed by most, as it only affected 0.08 percent of users, and even then did not affect normal delivery of email using client programs on Macs, PCs and iOS devices. The sending issue was only seen by users who were managing mail directly from the iCloud.com website. The Game Center problem was reported to be widespread (though not affecting all users), resulting in Game Center being "slow or unavailable" by Apple for generally brief but sporadic period throughout early Friday.
As of Friday afternoon (PT) all the issues were reported to be resolved. While all the big major cloud service providers -- Twitter, Facebook, Amazon Web Services and even GMail -- have had occasional outages, the high dependency on iCloud among Mac and iOS users means that any disruptions are second only to the very largest web services in terms of their impact, sheerly though the enormous size of the installed base of Mac and iOS users. Apple has said that iCloud now has over 250 million users (as of January), so even a problem that affects 0.08 percent may affect some 200,000 users. The company is said to be building additional data centers to help handle and improve iCloud's services.