The Apple Site search reveals that the new iPhone will be called iPhone 5. See the search result screenshot below.
It is official. The press-release that will announce the new iPhone is titled: "Apple Introduces the iPhone 5." Why do we know that? If you search iPhone-5 on the Apple site, you get as a result urls that contain iPhone-5. One of them is a link to a press-release that is not yet published. This means Apple will indeed call the new iPhone, iPhone 5. That is final.
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Additionally if you search for new-ipod-touch you receive a url to an unreleased press-release titled: "Apple Introduces New iPod touch and iPod nano".
Also Apple will issue a press-release for iTunes. This means there is a major iTunes upgrade coming this morning.
So Apple's eager site search index has confirmed the major rumors for the Apple Event starting at 10am PDT. This issue with the leaking Apple site search engine has been discovered by AppleInsider.
More Apple Event Highlights.