The Raspberry Pi 3 features a 1.2GHz 64-bit quad-core ARM Cortex-A53 SoC, integrates 802.11n WiFi and Bluetooth 4.1, and is compatible still with the Raspberry Pi 1 and Raspberry Pi 2. The Raspberry Pi 3 is making use of the Broadcom BCM2837 SoC. This 64-bit ARM development board still sadly only has 1GB of system memory.
The Raspberry Pi 3 is selling for $35 USD, the same price as the earlier RPi Model B units. A Raspberry Pi 3 Model A+ is expected later this year. There are quantities of the Raspberry Pi 3 available as of writing; in fact, prior to writing this article I already ordered a Raspberry Pi 3 for Linux benchmarking on Phoronix. So expect those Raspberry Pi 3 benchmarks on Phoronix in the days ahead.
More details on the Raspberry Pi 3 over at RaspberryPi.org.