The iPhone event may be held on Oct. 4. (© Paul Hackett/Reuters)

Coming from All Things Digital’s John Paczkowski is a report citing unnamed sources “close to the situation that pegs Apple’s iPhone launch event for Oct. 4.”

Sales, the report said, will likely follow within a few weeks.

There are two prevailing theories out there about the event: that Apple is launching a slightly revamped version of the iPhone 4, or it’s launching two phones — the upgraded iPhone 4 and a completely redesigned iPhone 5.

The event will reportedly be the debut product introduction for new Apple CEO Tim Cook, who’ll have to show the world what Apple really looks like post-Steve Jobs.

There’s some speculation that Apple’s chairman will make an appearance at the event if his health permits, Paczkowski said. A Jobs cameo is sort of a catch-22 — if he doesn’t show up, rumors about his health will likely flare up again. If he does make a cameo, people may read it as a sign that Apple’s having trouble with its transition.

As for sales, Fortune’s Philip Elmer-DeWitt suspects that the first phones will hit shelves earlier than the “few weeks” that All Things D’s report puts forth. Sharing an analyst write-up from Ticonderoga’s Brian White, Elmer-DeWitt notes that Apple has been steadily decreasing the time between iPhone product announcements and launches. The first iPhone was introduced 201 days after it was announced, while the iPhone 4 was in stores 17 days after its big reveal. And the iPad 2, which debuted in March, was in consumers’ hands within nine days.

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