Apple's yearly developer conference should see iOS 8, OS X 10.10, and likely some hardware.
Widespread Outages Reported for Apple's iOS and Mac App Stores and iTunes Store
A flood of MacRumors readers have reported in saying that they are having difficulties downloading content from Apple's online download stores, including the App Stores for both iOS and Mac OS X as well as iTunes Store content. The issues appear to be widespread although not universal, as others have reported that they are having no problems downloading content.
The reason for the downtime is not currently known, although speculation has of course centered around potential preparations for Apple's new iCloud service set to be introduced on Monday at the company's Worldwide Developers Conference. Such preparations could involve the company shifting content around such as to its North Carolina data center, moves that could result in some issues with access to the content. Alternatively, Apple could simply be experiencing some sort of network problems unrelated to new product and service launches.