In case you didn’t know, Apple is holding a media event on Tuesday, October 4 at 10am PST on their Cupertino campus. Based on the invitation send to the press and the teasing “Let’s talk iPhone” tagline, it’s pretty clear that this will be an iPhone event -- but exactly which iPhone(s) they’ll be talking about is still up for debate.

The rumor mill has been churning overtime in the days and weeks prior to Apple’s latest media event, which was finally announced last week with an invitation that clearly states “Let’s talk iPhone.” That graphic has been widely dissected across the blogosphere, with many believing the Messages badge displaying the number one as evidence that Cupertino will be unveiling only a single new iPhone.

But which one will it be? We’ve been subjected to rumors about an iPhone 5 for months, including detailed mockups of what it might look like -- although there is actually little evidence to support its existence. More realistically, Apple will debut a souped-up iPhone 4 the press has dubbed “iPhone 4S,” a name which is turning up left and right in the last few days.

Most recently, Cult of Mac reports that the iPhone 4S has turned up on Vodafone Germany’s website, listed in 16GB, 32GB and -- wait for it -- 64GB capacities. The carrier also lists a cheaper 8GB iPhone 4 model, which many widely believe Apple will use to mop up budget customers and better fend off the Android invasion.

That report seems to jive with two others over the weekend. First, 9to5Mac discovered a reference to the iPhone 4S hidden in the latest iTunes 10.5 beta 9 released to developers on Friday, which they claim could also be evidence that the new handset will cater to both GSM (AT&T) and CDMA (Verizon, maybe Sprint) customers with a dual-mode antenna. Regional carrier Cincinnati Bell also posted a few details about the iPhone 4S -- as well as an iPhone 5 with 4G HSPA+ speeds -- which some clever tipsters captured before they were pulled down.

The reality is, no one really know what Apple is about to unveil on Tuesday. While the iPhone 4S appears to be the most likely candidate, the iPhone 4 is nearly a year and a half old now after Apple skipped the traditional June release date. The idea of an iPhone 4S has solid evidence in Apple’s past -- namely the iPhone 3GS introduced in 2009, which was simply a souped-up version of the previous year’s iPhone 3G with a better camera, faster processor and new software.

There are a few details about the new handset that most of us are universally expecting, however -- a dual-core A5 processor like the one in the iPad 2, eight megapixel rear camera, 1GB of RAM and a built-in speech-to-text “Assistant” feature which has yet to turn up in iOS 5 betas and could be exclusive to the new hardware presumed to be introduced on Tuesday.

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