This chart shows price over the current block difficulty level. It shows that mining today is producing less than half the revenue that mining was earning earlier in the month. This is because since that time there were two back-to-back very high increases in difficulty.
At the same time mining currently brings in, per-day, about twice the revenue it did in mid-April – assuming the level of hashing produced by any specific mining hardware configuration remains the same.
The cost of electricity still isn’t the primary concern for most doing GPU mining. Using U.S. residential rates for estimations a typical miner configuration at the current level of difficulty sees the cost of electricity roughly at about 10% of the revenue the mining rig produces.
With these margins yet, it isn’t expected that miners will start powering down any time soon. After a few days since the last difficulty adjustment it looks as though the mining level has stabilized for the current price level. At the same time, miners probably won’t continue going nuts, as Steve Gibson so eloquently described the situation where miners expand their capacity.