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It's finally here. After months of rumors and speculation, the iPhone 5 will be unveiled today at 1 p.m EDT. There are plenty of features and upgrades which varying supply leaks have all but confirmed, but as always, plenty of unknowns remain. Let's take a look at what to expect today.

Count on it
The iPhone features which are seen as certainties today include a new 4-inch screen, thinner unibody construction, LTE support, and the newest version of Apple's (Nasdaq: AAPL) mobile operating system, iOS 6. In addition, search on Apple's site seems to confirm they'll stick with the iPhone 5 naming convention that's been expected and are also confirmed to be updating the Nano and iPod touch.

The obvious feature that's gotten the most attention is Apple's beefed-up 4-inch screen, which is larger than the 4S' 3.5-inch display. There has been no shortage of opinions taking Apple to task for not going with a larger screen, as best-selling Android models have gone as large as 4.3-inch screens.

My personal opinion is that those criticisms are off base. Just because a screen size is larger doesn't make it an improvement. From that standpoint, launch events like today are important for Apple because the company gets to set the narrative around product features. That is, Apple can use their launch event today as a platform to tell consumers why Apple feels a 4-inch screen is superior. Make no mistake -- events like today are very important marketing events.

LTE should also be a slam dunk and has been verified by several sources. Apple's communications supplier Qualcomm (Nasdaq: QCOM) has made big improvements on the size and power consumption of its LTE-capable chipsets. In addition, LTE deployments are taking off across the world.

At the end of 2011, just 47 operators across the globe had adopted LTE, but 150 will have it up by the end of the year. The biggest LTE bets have been made by American mobile giants, with Verizon (NYSE: VZ) up and running in 371 markets, AT&T with LTE in 53 markets, and Sprint (NYSE: S) racing to catch up with LTE in 19 markets, but aiming for 100 by the end of the year. Make no mistake, the iPhone's inclusion of LTE and the promise of more data revenue is driving the urgency of this arms race.

After those features, things get a bit more sketchy.

Don't count on it
One announcement that's been ruled out is Apple taking today's opportunity to launch an iPad "Mini." That product now likely will get its own event in mid-October. As an iPad Mini would primarily be competition to consumer-oriented tablets like Amazon's Kindle Fire and Google's Nexus tablet, it makes sense Apple would push an announcement closer to the holiday shopping season.

Another long-expected feature that probably won't make the cut is near-field communication. That's a market led by NXP Semiconductor (Nasdaq: NXPI) and embraced by many Android phones. However, with Apple not having put a bet on its own mobile payment system -- and NFC infrastructure still in its infancy -- it's likely Apple isn't set to embrace NFC just yet.

Interesting last-minute rumors
One last-minute rumor that caught my eye is an emphasis on the newest iPod touch as a gaming controller. There's always been a natural appeal to an upgraded Apple TV as a gaming console, as iOS devices are ubiquitous among American households, so iPads, iPhones, and iPod touches could function as remote controls or video game controllers. If Apple places an emphasis on this feature, it could be tipping its hand to future updates.

Guidance for the road ahead
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