> I'm not an expert, but I thought that these days you basically need specialized hardware/GPUs and a traditional botnet isn't going to get you that far. Am I right?
How many computers within that botnet will have the appropriate GPU? That's not counting the computing power of the network as a whole either; Imagine something like BitcoinMiner@Botnet. I think it could easily be lucrative enough to make it worthwhile.
The largest known bot net had ~30,000,000 computers at that scale CPU's work just fine. Not that it's the only thing to do with a bot-net of that size, but it's clearly a lower-bound where if your not doing a denial of service attack or sending spam you might as well mine bit-coins.
Assuming the average CPU runs around 2 Mhash/s that's 60,000,000 Mhash/s which is the equivalent of about 75,000 ModMiner Quad @800Mhash/s which would cost 75 million, so you would probably still top the mining charts.
How many computers within that botnet will have the appropriate GPU? That's not counting the computing power of the network as a whole either; Imagine something like BitcoinMiner@Botnet. I think it could easily be lucrative enough to make it worthwhile.