Take a look at
http://www.devtome.com/doku.php?id=cpu_miningEven a raspberry pi or a beaglebone or something on that scale can be very competitive, and it still looks like it will resist botnets quite well for quite a while yet.
You should always bear in mind that pretty much any "make money on the internet" scheme is only a certain size of pie so the more people who start taking a slice of the pie the less pie they each get. Thus ideally you want things that the masses of computer-illiterate Windows-user types are going to think is too complicated or too hard or not GUI-enough; as once even the most illiterate such users can just "plug and play" the pie gets sliced up into so many parts the amount each slicer gets is so tiny as to hardly be worth bothering with.
This system takes advantage of that by deliberately using a text-type API without the overhead of graphics, so that you can do more stuff with less processing power and bandwidth and, maybe more important, the people who insist everything has to be GUI/graphical will turn up their noses at it, thus leaving more of the pie for people who are literate.
-MarkM-
