I read about this on hardocp.com and starting mining 2 days ago. I don't have an amd/ati card yet though, so with my nv460 and nv470 I've earned about .18 Bitcoins. Which at today's current value is worth about $2.47 I'm picking up a 5770 tomorrow and have a 5830 on order. Those should generate about 4 to 5 times what I can do with my 2 nvidia cards. So.. I might be able to make about $4-$5 a day. So $120 to $150 a month. I don't pay for power. In one month I could pay for the 5830 and I'm getting the 5770 used, so another 2 weeks to pay for it. If I can make enough to pay for the cards before the bitcoin value plummets, I'll have just got me 2 free video cards. If I don't make the money back, at least I have 2 cards and maybe some money towards them. I'll see what happens.