Official Raspberry Pi Page
4 USB ports
3.5mm jack for audio & composit video out
SoC is a Broadcom BCM2835
This contains an ARM1176JZFS (ARM11 using an ARMv6-architecture core) with floating point, running at 700Mhz, and a Videocore 4 GPU.
The first version of the GPU used came out in 2009.
Capable of BluRay quality playback, using H.264 at 40MBits/s.
Has a fast 3D core accessed using the supplied OpenGL ES2.0 and OpenVG libraries.
Provides Open GL ES 2.0, hardware-accelerated OpenVG, and 1080p30 H.264 high-profile decode.
Capable of 1Gpixel/s, 1.5Gtexel/s or 24 GFLOPs of general purpose compute and features a bunch of texture filtering and DMA infrastructure.
That is, graphics capabilities are roughly equivalent to Xbox 1 level of performance.
Overall real world performance is something like a 300MHz Pentium 2, only with much, much swankier graphics.