if you have a decent electricity cost you can give a shot to mining with little risk with some second hand GPUs to see if it's worthwhile, and easily resell the gpus with little loss if you find that is not. Or you can mine just in the winter to have "free" heating. I wonder what the fpga crowd will make of their investment if something goes wrong.
There are a lot of interesting sides to the entire BitCoin economy. I wish I had been involved in the GPU hay day simply because I love building custom rigs. I think I going to order a BFL just for fun and if it never pays for itself Ill live and if it does Ill buy more. I have pretty cheap electricity and another project Im working on is Solar/Wind for my home. I don't have any delusions of getting rich but I just want to get involved on as many angles as i can for the fun of it.