First off, we don't know the official name of the device, but one can probably expect it will have something to do with iPhone 4, 4G (although 4G support isn't expected quite yet), HD, etc.
The design of the prototype that Gizmodo.com got their hands on was quite different from the previous iPhone design. It didn't have the familiar rounded bezel, but rather a flat hard-edged design. It looks rather 'boxy' and un-Apple like in design, but it does give a nice refresh to the iPhone look if it turns out to be true.
Besides that, the buttons are all metal along the sides, with the volume adjustment now being two separate buttons instead of a rocker switch.
The screen design is mostly the same, although it does seem to have a higher resolution, with the most popular rumor of it being 960 x 640 pixels.
The much talked about front-facing camera seems to be coming true it seems. In the device that Gizmodo found, Apple seems to have included a front-facing camera that Apple will use for video chatting in its upcoming iPhone 4.0 OS. There's also been some evidence in the SDK of OS 4.0 of a front-facing camera too.
Image Credit: Gizmodo.com
When Gizmodo teared apart the device, they were unable to determine what processor the new iPhone 2010 uses and exactly how much flash memory is inside the device. The back of the prototype had "XX GB" printed on it, so that isn't much help. Some rumors point to 80GB, but that isn't a typical number for storage as it's usually in powers of 2. So in terms of storage, there's no definitive answer.
The phone also makes use of the new MicroSIM instead of the conventional SIM cards that have become widespread. MicroSD cards are smaller than conventional SIM cards which means Apple was able to free up some space for other internal components. There is also no definitive answer on 4G compatibilities, either AT&T's LTE network or Verizon's 4G network. Although it can be said that Verizon's 4G network isn't ready for use yet across the United States, but by 2011 it mostly likely will. We can probably say that no Verizon iPhone will be available this June, but probably in late-2010 or early 2011 we will see a dual 4G & CDMA iPhone.
The battery of the prototype iPhone 2010 also has changed in terms of size: it's 16% larger. There's no word yet on how long it lasts in normal use, but we can expect it will be longer than the iPhone 3GS's battery life.
The software that the iPhone 2010 will run has already been announced by Apple and we know mostly everything there is to know about it. You can read our rundown of all the changes in the iPhone 4.0 OS instead of us posting all of it here.
It's pretty safe to say the retail release of the iPhone 2010 will be late June after the June 7th announcement. In the past Apple has released the first 2G iPhone and 3GS iPhone in June and the 3G version in July. The iPhone 4.0 OS software will most likely be released just days ahead of the iPhone 2010 release if the usual pattern follows.