IF those numbers are correct, it might be a bit underwhelming. 2048 shader processors @190W vs 1600 @188W for a 5870. Clocks are virtually identical. Assuming identical performance per shader per clock (I know, huge assumption) thats a nice improvement but not quite the quantum leap some may have hoped for.
The 79xx series use a completely different architecture (GCN). You can't compare them clock to clock and shader to shader.
The bad news is that the new shaders are much more like Nvidia shader (more complex, more capable) which doesn't bode well for mining performance. Each shader is more powerful but most of that power is wasted for something as simply as computing a hash round.
The 78xx series use the same exact architecture as the 6000 series (VLIW4). Just smaller, cheaper, faster, cooler. So IF there is a good mining card is likely will be in the 78xx series. The 7850 looks like "the card" at least on paper. Still I wonder how popular that will be. Gamers have been waiting a long time for a die shrink so expect to see a lot of cheap used hardware. Cheap used hardware plus 2012 being the year of the FPGA I think the 7800 cards won't be adopted heavily.
Now maybe (longshot) AMD new architecture will amaze us but I think the 79xx will be duds for mining, although awesome for gaming (and maybe more complex GPGPU tasks).
