This has an identical form-factor to the existing Raspberry Pi 1 Model B+, but manages to pack in both the new BCM2836 and a full 1GB of SDRAM from our friends at Micron. All of the connectors are in the same place and have the same functionality, and the board can still be run from a 5V micro-USB power adapter.
The Raspberry Pi 2 features a 900MHz quad-core ARM Cortex-A7 CPU and 1GB LPDDR2 SDRAM. Since the device has an ARMv7 processor, it can run the full range of ARM GNU/Linux distributions, including Snappy Ubuntu Core, as well as Microsoft Windows 10. The team has been working with Microsoft over the last six months to bring Windows 10 to Raspberry Pi 2. The Raspberry Pi 2-compatible version of Windows 10 will be available free of charge to makers.
At launch, the same ARMv6 Raspbian userland is being used on both Raspberry Pi 1 and 2. Over the next few months the team will investigate if higher performance can be obtained from regular ARMv7 Debian, or whether it's possible to selectively replace a small number of libraries to get the best of both worlds.
You can purchase the Raspberry Pi 2 from element14 and RS Components for $35.
More details on what is Raspberry Pi can be found here.