Robert Scoble has an interesting post in response to Om Malik's suggestion that Twitter start charging "Super Users". Scoble would qualify as an edge-case when comes to social network . He has a history of hitting the limits like these on MSN Messenger and Facebook.
Charging seems like an acceptable action to take for users like Robert who use these services at such a level. Robert is obviously getting business value out of these services and it is perfectly reasonable to get revenue from that. But I agree with Robert when he says that this won't completely solve their scalability problems. The amount they would have to charge would likely exceed the value of the service.
I also hope that Robert is correct in his assertion that Twitter's problem isn't caused by how it manages the data. If Assetbar is correct in his description then Twitter has a problem. I have no knowledge as to how Twitter works under the covers but I sure hope Assetbar's description isn't accurate.
I think we need to add another level to our description of scale: Small, Large , Enterprise and now Scoble Scale. Maybe he should rent himself out as a testing framework for social networks...