I haven't tried mining on the 480s, only on V6 240s.  The reason behind this is I have a handful of unused boards that have V6s on them, while the K7 boards are all used for my real work.

I made an entry in the mining hardware comparison long ago:

The V6 240s run at 375 MH/s at about 16w.  This isn't optimized (other than to use some DSP48s), so I guess you could probably squeeze another 50-100 MH/s out of the devices with some effort.

The MH/s based on the size of the device breaks down as follows:

375MH/s / 240 = 1.5625 MH/s per "size unit"

Based on this, I would estimate the 480 could do:

480 * 1.5625 = 750 MH/s

I haven't used Xilinx's power estimator for a K7 bitcoin design, but Xilinx claims 50% less power than the V6.

So, you could assume your worst case would be 32w, best case 16w.  Somewhere in the middle will probably be your actual power.

BUT!!  You may think the Kintex 7 would be better for mining (price/performance) than a Spartan or Artix device, but you'd be wrong!

Take the Mod miner for example:

840 MH/s @ 40w in 4 x Spartan 150 devices

840 MH/s / (4 * 150) = 1.4 MH/s per "size unit"

So, the S6 is a little less efficient in terms of size/performance (partly because I used DSP48s in the V6 example to reduce logic usage, but there are other factors), but the price difference is huge.  I think the S6 LX150 is ~$100, so there's no real good reason to buy the K7 or V6.  The K7 and V6 provide more advanced functionality (high speed serial, more internal memory, more DSP slices, more pins, etc) that aren't required for bitcoin mining.  You'd end up paying for features you don't use.

Once the Artix devices come out in force, I suspect they will be similar in price/performance to the S6.  Power consumption will be somewhere between 50% less and the same as the S6.  However, they are the last devices to go into production (after the K7 and V7).