Businessweek cites an analyst with iSuppli that the iPhone may be seeing some minor delays due to ongoing issues. According to Jagdish Rebello, "various iPhone suppliers have been told that the iPhone may not be available until the end of June."
We're hearing it's mostly an issue with the complexity of the device, and that all the component suppliers are making their deliveries on time
While many have speculated that the iPhone would arrive near the Worldwide Developer's Conference which starts on June 11th, Apple's most recent statement indicates that the iPhone would be ready in "late June as planned". (Updated)
Rebello speculates that the delay in Leopard was prompted by an unexpected shift in personnel from Leopard to the iPhone: "It's clear they have found some issues that they need to fix." Another analyst who has tested the phone states that they didn't uncover any problems with it but points out that "Apple wants to get it right the first time."
Meanwhile, Shaw Wu believes that the Leopard delay was due to the "secret" features that have not yet been revealed: "Our analysis indicates that if not for the 'secret' features, the core Leopard operating system would likely have shipped on time."
Update 2: A speculative Mac Observer post by John Martellaro (ex-Apple employee) attributes some of the timeline issues to poor staffing by Apple.
Apple, despite being a large and wealthy company these days with likely more than 18,000 employees, is actually a very lean organization. And that lean configuration has been maintained, even though the demands of the iPhone, the Apple TV and Leopard would have suggested a moderate increase in staffing. Despite all better judgment, Apple hates to ramp up to meet these kinds of expansions in the product profile.
Update 3: A Smarthouse article goes into more depth than the Businessweek article but touches on the same topics. Specifically, battery life of the iPhone has been up for debate with the complexity of the iPhone's software, according to this report.
