It's a rumor, not a fact and that makes a big difference to me.
Also, what is a MM ?
On the other hand, as MixPanel pointed out, they buy a LOT of traffic. Not just on Myspace either. On both networks you can build a compelling enough game to get your RPU above the cost of buying a user. The difference between the two is that on Facebook, your app can succeed without that.
Zynga's spending what has to be at least $2m/mo in ads, maybe 3 or 4. They're also using ads on their games to cross promote with other games, and those ads could be bringing in money too. When you factor that in, as high as 50% of their revenue could be going right out the door to advertising. (I don't think that's the case though, if I had to venture a guess I'd say 20-25%).
I prefer M = mega = 10^6, as in SI units.
A side effect is that it forces people to think in powers of a thousand. Not so long ago a show interviewed people about the economic crisis, and the value of a trillion, and how much more it is than a million. Most people weren't even close, and believed a trillion = a thouand million. So I like the more scientific notation of 2mm, or 2mm mm, becuase it shows people instantly that 2mm (two million) and 2mm mm (two trillion) are mm -> a factor million apart.
Don't know how it is in Europe, but few in America would recognize 2mmm to mean 2 billion.