Apple's iWork for iCloud service may be inaccessible at times for some users as Apple deals with an overwhelming response to the service.
At WWDC in June of this year, Apple introduced iWork for iCloud, a service that brings a large number of the features in Pages, Numbers, and Keynote to iCloud.com, making documents, spreadsheets, and presentations accessible and editable through most major browsers.
This service was at first limited to developers, but Apple sent invites to a number of Apple customers, allowing them to use the beta release of iWork for iCloud. However, it appears Apple did not anticipate the popularity of the iWork suite, which it describes as being overwhelming, and resulting in some users being limited in access to the suite.
When logging into iCloud.com to access Pages, Numbers, or Keynote, some users may be met with an error message that denies them access to the service, and claims that an overwhelming response is the cause. While the programs themselves will not be accessible during this time, you should still be able to use desktop and iOS versions of the iWork suite to access your documents stored at iCloud.com.
Hopefully Apple will increase the capabilities of its iWork for iCloud servers, and get everyone who uses it a smooth and seamless experience, though in fairness the service is still branded as a beta, which inherently brings the potential for problems like this.