Don't miss the forest for the trees. If it wasn't skype, it'd be some other channel. The point here is that mining malware is a rather new and troubling phenomenon.

And of limited real value. A CPU only miner would yield about 10 MHash/s or less on standard hardware, and a malware/junkware loaded PC will do even less.

I recently came across a very naive-looking sample of a pooled GPU-miner being distributed via a purported crack for a certain EA game.

It's ridiculously easy to implement GPU mining if you have any remote execution on a machine.

Isn't the total hash rate the sum of the hash rates of all infected machines (i.e: 10MH/s * 2000 infected machines = 20GH/s)?

Far less than that. My shiny quad core i7 gets 4MH, and I doubt most consumer desktop computers would manage that. You're probably looking at 0.5-2 at a maximum.

There will always be ways to monetize malware. I'd rather they monetize it by mining Bitcoins than by doing something more destructive.

honeypot anyone... create the appears of a hacked machine that is successfully mining... keep'em busy for a few weeks ...

It's surely automated, in which case, there's nothing to "keep busy" like a human manually hacking into the average lousy computer one by one.