The iPhone Developer Center was temporarily unavailable on Wednesday morning, accounts say. Although once again active as of this writing, earlier visitors to the site are reported to have seen Apple's standard "we'll be back soon" graphic, and been unable to access normal developer services. The Center would normally allow developers to check on their App Store submissions.

The downtime is likely connected to a slip-up from last night, in which placeholder licensing text made reference to a product launch scheduled for later today. Together the anomalies may suggest major changes for the iPhone OS, which is widely expected to evolve to support a forthcoming tablet. The CEO of book publisher McGraw-Hill may have inadvertently confirmed the information.

MacNN is set to cover today's Apple press event live; while coverage will begin early, the event itself should start at 10AM Pacific time, 1PM Eastern.