Mark your calendars for Oct. 4.

AllThingsD reports that Apple (Nasdaq: AAPL) is expected to unveil the better-late-than-never iPhone 5 on that fateful Tuesday during an event hosted by CEO Tim Cook. This year, Cupertino has departed from its tradition of announcing the latest and greatest model each summer, although the company had a minor debut in January, when it broke its monogamy with AT&T and let Verizon in on the action.

What can we expect to see in the iPhone 5? Let's start by looking at some significant components found in the current iPhone 4 and go from there.

  • Skyworks (Nasdaq: SWKS) and TriQuint power amplifier module.
  • Broadcom Wi-Fi, Bluetooth, and GPS chips.
  • Samsung flash memory, DRAM memory, and manufactured ARM-based A4 chip designed by Apple.
  • Cirrus Logic (Nasdaq: CRUS) audio codec.
  • Texas Instruments touchscreen microcontroller.
  • OmniVision (Nasdaq: OVTI) rear-facing 5 MP backside illuminated CMOS image sensor and front-facing VGA camera.
  • STMicroelectronics 3-axis accelerometer and 3-axis gyroscope.
  • Intel-owned Infineon supplies the baseband for the AT&T model for its GSM network.
  • Qualcomm (Nasdaq: QCOM) world-mode baseband in the Verizon version that supports both GSM and CDMA networks like Verizon's.
  • Corning (NYSE: GLW) Gorilla Glass.

This isn't a comprehensive list, but it's a good starting point to speculate on who will win spots in the iPhone 5. Some of the suppliers are unlikely to change, while others are almost certain to. Samsung still fabricates the A5 chip found in the iPad 2, so it's practically a sure bet to do the heavy lifting. Taiwan Semiconductor Manufacturing is rumored to manufacture the next two generations, the A6 and A7.

Say "Cheese"!
OmniVision bears have contended that the iPhone 5's camera will be dual-sourced, with Sony sharing the spot. I've owned and followed OmniVision for quite a while, and these rumors pop up every few months, and the company gets punished hard each and every time. The latest selloff provided enough of a discount for one Fool to pick up shares for himself.

The company's second-generation BSI sensor was unveiled earlier this year and scheduled for mass production during the second half of the year. I've actually thought one possible reason for a late iPhone this year was specifically to be able to include these next-generation sensors.

We all know that Apple is a perfectionist of a company, and the dual-sourcing hypothesis opens up the potential for inconsistent user experiences among the models if the sensors perform differently. The iPhone 4 camera solely provided by OmniVision has gotten loads of praise. Why mess with a good thing? My official prediction is that in spite of weak guidance scaring investors off, OmniVision will be the sole supplier of an 8 MP BSI-2 rear-facing sensor.

One for all
The inclusion of Qualcomm's world-mode baseband in the Verizon iPhone 4 is notable because it was one instance where Apple may have revealed its hand early, if you don't count losing prototypes in bars. Right now, iPhone 4 comes in two flavors: CDMA (Verizon) and GSM (AT&T).

Chances are that an updated dual-mode baseband chip will be in one single iPhone 5 model and will be able to run on any 3G network you throw at it, displacing Infineon. The unified chip would eliminate the need for two separate models and the associated manufacturing inefficiencies. By coming out mid-product cycle, the Verizon iPhone gave us a glimpse of what Apple may be thinking as the iPhone evolves.

New and improved
When it comes to totally new features beyond incremental spec bumps, there are two possibilities that stand out in my mind: 4G LTE and near field communications, or NFC.

AT&T and Verizon have been aggressively building out their 4G LTE networks, but they still remain inchoate in the grand scheme of things. Right now, AT&T's 4G LTE covers only five cities and is aiming for 15 by year's end, while Verizon boasts 143 markets with a goal of 175 throughout 2011. Add in the fact that 4G technology is so young and that its speed comes at the expense of battery life -- which Apple puts high on the priority list -- and the prospects of seeing 4G in this year's iPhone start to dwindle. Of course it's possible, but I think this one will have to wait until the iPhone 6, when LTE has better coverage and technology.

When it comes to NFC, it also lacks any meaningful infrastructure, just like 4G. Google just launched its Google Wallet service, which uses NFC, while eBay's PayPal chose a different route to get physical. Adding the technology would be a boon for NFC chipmaker NXP Semiconductors (Nasdaq: NXPI), but there's really no rush to include it, since most merchants and payment processors haven't fully adopted it.

A broken crystal ball
I have no way to predict the future. These are merely some of my educated guesses. This year's iPhone 5 will certainly see some basic specification upgrades and maybe even a redesigned case with a larger 4-inch screen. Of the two new features mentioned, I think only NFC would make it, if at all. We'll know for sure once it's released and subsequently torn asunder.

Apple also has a penchant for throwing us a curve ball occasionally and catching us off guard with features we didn't even know we wanted, so there's always the chance that Cupertino will do something no one expected.

What do you think? How will Apple improve the iPhone? Share your thoughts in the comments box below.