I updated that forum post with new numbers showing that at the current difficulty it might cost over $700 to generate a single block, and at the estimated difficulty which will happen tomorrow, it will cost over $1000 to generate a single block.
Generating a block currently gives you 50 bitcoins that are worth about $45 at the current market price.
I guess you mean for CPU mining? Mining with a GPU is definitely profitable.
That's why the difficulty keeps increasing; mining is so lucrative that an ever increasing number of people are getting on board, which drives up the difficulty.
Generating a block currently gives you 50 bitcoins that are worth about $45 at the current market price.