http://www.techweekeurope.co.uk/news/zeroaccess-bitcoin-botnet-sinkholed-128... Zeroaccess was a botnet that did a bunch of things, such as fake ad clicks and Bitcoin mining. A DNS sinkhole was created to attack its DNS-based communications, which took out about 1/3 of the botnet. One side issue that I found interesting, besides the usual security stuff, was the assertion that "The botnet's Bitcoin operation was only profitable because it used stolen electricity: it used about $561,000 of electricity a day on its victims' machines, while only generating $2,165 a day." What does this say about the future of Bitcoin mining? I'm guessing that the botnet only mined on CPUs, not on GPUs, because doing GPU calculations requires adapting code to different kinds of hardware and is likely to have visible effects on the screen if you're not careful, but even so, does this mean that Bitcoin miners who want to make a profit are going to need to dump general-purpose machines in favor of specialized hardware such as FPGAs or ASICs? Or is buying a high-end GPU still good enough?