Nobody has mentioned yet the risk of the ASIC that different groups have announced for the end of this year begginning of the next one. When that hardware is ready your GPU wont be able to compete and will be an obsolte investment. And the prodcution is halving every 18 days because of the increase of difficulty. If you are not able to break even under those conditions by the end of the year, you should think very carefully what you are doing, otherwise you are going to loose money since you wont be able to keep your GPU generating (profitably).

There is only two things that can change to make mining profitable. 1) The difficulty stops growing so much giving miners some room to get more bitcoins. 2) The price rises consierably, to $30 and beyond.

(This part is speculation obviuosly) Regarding 2) I dont see that happening for a long time, probably until 2012 because the initial rush because of the press has happened and there is a lot of people looking to unload in the $20 range and beyond. It will take time and a lot of demand to break that resistance. Also, the kind of people the rush has attracted to Bitcoin is not people looking to improve the Bitcoin economy, but a lot of those are looking for a quick and easy way of making money, so when the price rises to those levels they will sell.

Regarding 1) is the part that I see more posible to change. I still dont understand how anyone can be buying dedicated miners at this point, so it makes sense to me that at some point not so much capacity will be added to the network and the difficulty will stop growing so much. I really dont understand some people that are buying and buying GPU's right now. What are they going to do with their 50+ gpu farms when the ASIC chips make their hardware obsolete? But again, its not guranateed that the difficulty will grow slower, for all we know it could grow even faster. But I think its more probable that we see the difficluty slowing than the price rising a lot in the rest of 2011.

But anyone has to keep in mind that if there is not a big change in the difficulty trend or in the price, buying a dedicated miner right now is NOT profitable, you wont break even. Anyone can do the math.