Every tech company out there is hell bent on making thin gadgets, whether they're phones, tablets, consoles, or whatever. With the Raspberry Pi Zero not offering as much as its big brother,the Pi 3, one hacker, known as N O D E, took it upon himself to fix the issue. So he slimmed down the Pi 3 to produce the Raspberry Pi 3 Slim.
The Pi 3 Slim is about 7mm thick, though this skinny form-factor is not without compromise. That means most of the ports are now gone, including the full-size USB ports, ethernet, the HDMI port, and GPIO pins. N O D E soldered on two more micro-USB ports to try and make up for it, which join the original micro-USB port (used for power) and the micro-SD card reader.
So your options are a lot more limited than the standard Pi 3, which isn't all that big anyway, but you don't need GPIO pins or video output to put a mini computer to good use. It's helpful, but not essential if you know what you're doing. It also needs a case, which you'll have to 3D-print.
Maybe this isn't the kind of thing a beginner will want to craft for themselves, and since you can't buy it you'll probably have to do with the official Pi boards for the foreseeable future. But anyone who knows what they're doing (and knows how to use headless systems) could try and make one for themselves (if they're brave enough), even if N O D E doesn't seem to have released step-by-step instructions. [N O D E via Slashgear]