"Alex has produced a new Raspbian release, which integrates a number of recent improvements. Along with kernel and firmware updates, highlights include: Sonic Pi is pre-installed so you can jump right in to learning to program while creating your own music; significant performance improvements to Scratch; a build of PyPy 2.1 is now included to allow you to try out this high performance Python JIT compiler; Python libraries required for interfacing with Pi-Face are pre-installed. Due to the addition of Java, the standalone SD card image now requires at least a 4 GB SD card, as with 2 GB there’s not enough free space left to be useful."
Raspbian is a free operating system based on Debian GNU/Linux and optimised for the Raspberry Pi hardware (the armhf processor architecture). Raspbian comes with over 35,000 packages, or pre-compiled software bundled in a nice format for easy installation on a Raspberry Pi. The initial build was completed in June of 2012, but the distribution continues to be active developed with an emphasis on improving the stability and performance of as many Debian packages as possible. Although Debian produces a distribution for the arm architecture, it is compatible only with versions later than the one used on the Raspberry Pi (ARMv7-A CPUs and higher vs the Raspberry Pi's ARMv6 CPU).