Disclaimer: If you are reading this because you thought I am talking about "raspberry piE" then I am sorry to disappoint you . This is about "Raspberry Pi" the computer! For PIE here is the top result.
Wow where to start. Guess an introduction first. The Raspberry Pi is a cheap (around $35) computer that comes as an open circuit board. You get to see the components in the nude, touch the chips and components (not recommended due to ESD and a little shock ) and even add other compatible boards to it.
What makes the Raspberry Pi so special? For one it is quite powerful (taking price and size into consideration of course). It comes with a Broadcom BCM2835 (SoC: CPU, GPU and RAM sandwiched on a chip), 256MB of RAM that can be split between OS and the GPU, 2 USB ports, an Ethernet port, HDMI output (yes, the GPU has enough juice to output 1080p video), RCA video output and the popular 3.5mm audio jack. It also comes with GPIO (General Purpose Input / Output) that will let you connect to other boards (some available, others coming). All you need to run the OS is simply an SD card! And it only needs 3.5W from a USB power supply to run it (the micro USB type B available on some phone chargers today). Basically all you need is any TV with either the old video input or HDMI and a USB keyboard and mouse (or you can simply use Ethernet (it comes with a 10/100 port) for SSH and get rid of the keyboard and mouse).
It took quite a bit of waiting for me to get my Raspberry Pi. I actually had to register on a waiting list (many months ago), when it was my turn (invited to order on the 21st of June) I ordered and paid in full but had to wait a bit longer (16th July) before they shipped my Raspberry! It was also the first time any of my Aramex Shop and Ship packages had to go through customs (a circuit board definitely looks awkward, especially these days).
Software wise, the Pi runs Linux for now. A wide range of distributions are available, the more popular and recommended one being Raspbian (Raspberry + Debian). A more complete list of distros available may be found here (including some media servers). I opted for the recommended Raspbian, that comes with an LXDE desktop. To be honest, the desktop is slow compared to one of those cheap Chinese tablets running Android. However, if all you need is the shell then the Pi is for you.
Given that the Raspberry Pi is targeted for kids and for educational purposes, it does have its applications in other areas. Here are just a few current and upcoming projects based on the Pi.The official site also showcases what people are doing with their Pis. At the moment I have decided to run my Raspberry Pi as a seedbox: no more noisy, power hungry PC left running overnight !
Here are a few great links for the Raspberry Pi: