Whatever the price of electricity, consider this:
The difficulty of mining is exponentially increasing. Say it doubles each 10 days. Assume you want to buy a radeon 5870 to do the mining. Its currently the best card for the money on the second hand market (180 Eur).
Now during the first 10 days it will produce 4 BTC (this is actually close to the real value). The next 10 days it will be 2 BTC, then 1 BTC etc. See how 2 + 1 + 0.5 + 0.25 + 0.125 is getting closer to 4 but not really ever getting there? In total, you will not ever got more bitcoins than 2* the earnings during the 10 first days.
Similar relationship will apply whatever the speed of difficulty increase is, as long as it is exponential. And so far it pretty much has been. In other words, your 180EUR card will not earn more than 8BTC, which is about 100EUR today. So this is an investment that will cost you, unless the value of bitcoin dramatically increases. On top of that comes the electricity bill of course.
0.6KW*24h = 14,4kwh a day, at a price of 2.88$ a day.
As of today, 20th of june 3 5850s at around 750Mhash/s will earn you 1BTC per day. Thats about 15-20$ today, so you will make a win against the electricity bill. Assuming the difficulty will be exponentially increasing 3 times more from now ( should take around around one month), the same hashing speed will make maybe 0.1-0.2BTC per day (that is in august). With today's BTC price, this would mean you will be barely braking even, and have generated around 18 BTC (300$) in the process.
If you continue after that, you will be increasing your loss, hoping that the BTC will be worth MUCH more in the future, so you can pay back the ~700$ you spent on the 5850's.
Only thing that can stop this from happening is that people stop increasing their mining speed, so the difficulty will stop increasing that fast.
But it is unlikely to happen within next 8 weeks, and then it is too late: mining will cost more than the electricity it takes.
You can do it for fun, but it is not easy profit anymore. Maybe you will profit in the far future, but it will cost you a lot of investment and risk.