The HD 5670 apparently has 400 shaders, 16 ROPs, a fillrate of 103.3 GTexels/s and 64GB/s of bandwidth. It sports 1GB of GDDR5 memory on a 128-bit bus. The memory is clocked at 1000MHz (4000MHz effective), while the 40nm GPU ticks at 775MHz. The specs remains unconfirmed. Here is a glimpse of the card which looks rather neat.
It is expected to be launched in Q1 2010 and should be sub US100.