I rarely link to rumors or leaks because:

• Who knows if they’re ever true (many rumors are simply sensationalized posts pulled out of thin air in hopes to lure in some page views).

• New rumors sprout up every day, and I have no interest in playing that game and giving momentum to the rumor mill.

• Rumors have no effect on what the real product will be, when it will be released, or if it will even exist.

• Reading rumors is like shaking your Christmas present boxes and trying to guess what’s inside. Sure, there is an element of fun and mystery that comes along with trying to guess what’s inside. But if you do guess then it ruins the surprise. I much prefer surprises.

However, today there is so much flying around about the potential design of the iPhone 5 that I thought it was worth highlighting and sharing a few of my initial impressions.

Today Mac Rumors posted some 3D renderings of what the iPhone 5 might look like. They commissioned CiccareseDesign to do the renderings based on recent leaks of an iPhone case.

Also, a couple days ago this video was posted which claims to demo the leaked iPhone 5 website right on Apple.com.

As cool and polished as the video of the leaked website is, it is a fake. The Mac Rumors 3D rendering doesn’t claim to be a leak at all. In fact, I think what they did is very clever and their renderings look great.

The design of the iPhone 5 seen in the fake video is very similar to the 3D renderings that Mac Rumors commissioned. They are both, more or less, branched off of the original iPhone 5 mockup posted by This is My Next back in April.

In short, the general idea with all these various rumors and mockups is that the next iPhone will: (1) be thinner; (2) have a teardrop-shape making the top-end of the phone thicker than the bottom; and (3) implement new technology and functionality on the front where the Home Screen Button is.

What I like about the rumors of the next iPhone:

• The idea of a curved back. I think the iPhone 3G and 3G S were much more comfortable to hold than the iPhone 4 is. Though I am significantly more fond of the iPhone 4’s design — it is very classy and sturdy; the iPhone 3G S felt much cheaper.

• A thinner design. Who doesn’t want thinner and lighter mobile hardware? Though I have a hard time imagining the next iPhone to be as thin as the current iPod touch.

I have an iPod touch and it is thin. In fact, I’d say it’s almost too thin to be a phone. A phone needs to be extremely grip-able because it’s something you are constantly putting in and out of your pocket, waving around, texting with while walking, and more. To me, the iPod touch is not as easy to hold on to as the iPhone 4.

• The matte black aluminum back. It would be so sweet looking. (But, as you’ll read in a minute, I don’t think it’ll happen.)

• A more useful and functional home button. I think we’re all agreed that the home button functionality is getting broken and that there could be a better way to quickly switch between apps, especially when there are two or three apps you are using simultaneously.

What I don’t expect to see in the next iPhone:

• Extreme thinness. The iPod touch is significantly thinner than the iPhone 4, but it comes with tradeoffs such as a lower-quality camera. Combined with the current state of battery technology, the need for a CDMA or GSM chip, and the other bits that the iPhone 4 which the iPod touch does not, and I have a hard time believing the next iPhone will be as thin as an iPod touch.

• An Aluminum back. As cool as I think it would be, the reason Apple moved away from the aluminum back in 2008 was for the sake of needing better cellular connectivity. Do you really think Steve Jobs wanted a plastic iPhone? No way. But they needed to use plastic on the the 3G and 3G S for the sake of functionality and improving cellular connectivity.

• A 4-inch screen. With a screen that big, it would no longer be a “retina” display. A 4-inch screen with resolution of 640×960 would have a pixel density of 288 PPI. The current pixel density of the iPhone 4 is 330 PPI. That would mean a 4-inch screen would suffer a 13% loss in pixel density — the same loss that’s found between the 13-inch MacBook Air and the 15-inch MacBook Pro. And if you’e ever set those two laptops side by side the difference is instantly obvious. (I even said in my MacBook Air review that the 15-inch MacBook Pro now looks comically large.)

According to Apple, the whole idea of the Retina Display is that after 300 PPI our eye can’t tell the difference. So, according to that theory, they are technically safe to drop the pixel density just so long as they keep it above 300. If they were going enlarge the screen it would have to be no bigger than 3.8 inches.

If they did go to a 4-inch screen, in order to keep it a Retina Display they would need to increase the pixel resolution to something other than 960×640, and there is no way that’s going to happen.