As the launch date for the iPhone 5 gets closer, certain details about the new phone’s design appear to be firming up. Or, if not firming up, then at least getting repeated more widely, and from an increasingly diverse array of sources. Some of the most common ones include a larger screen and some kind of metal rear panel.

Today, iLounge has published details of the new iPhone, and they appear to confirm many of the rumors. According to iLounge’s sources (which have proven pretty reliable in the past), the next iPhone will, in fact, have a 4-inch screen. The new phone will apparently make room for the larger screen by getting a height boost of 10 millimeters – from 115 millimeters to 125. Width is reported to stay virtually unchanged.

The new iPhone is also, it seems, going to get a metal panel on the back. Interestingly, only part of the rear panel will be metal – a metal plate near the middle. The upper and lower portions of the rear panel will be made of some other material – plastic or ceramic, most likely. If true, this is a fairly unusual move for Apple. Historically the iPhone’s rear panel has been one single piece (be it plastic or glass). Blending two different materials in one rear panel is a design choice that Apple has tended to avoid (with good reason).

Height isn’t the only dimension that’s likely to change, apparently. The next iPhone will continue Apple’s preference for making its gadgets thinner and thinner with each major redesign. While the iPhone 4S is a fairly hefty 9.3 mm thick, the new iPhone will be 7.4 millimeters, a reduction of around 20%.

Finally, iLounge’s report confirms a rumor that’s been around for several months: a new, smaller dock connector. While the current dock connector on iOS devices has 30 pins and is fairly wide, this one will have fewer pins and be significantly narrower. The reason for the narrower connector is a matter of real estate: the smaller connector would take up less space inside the phone, making a little extra room for things like 4G radios, a larger battery, or any number of other components.

While this is all still just rumor, the fact is that iLounge has a pretty good track record. Though they don’t have a perfect record, they’ve often been right about the details of upcoming products. If they’re right this time, then it looks like Apple really is finally abandoning the 3.5-inch screen that they’ve held onto through five generations of iPhone.

What do you think? Would you like to see a 4-inch iPhone? Can Apple make the iPhone thinner and still fit a 4G radio inside? Let us know in the comments.