It would be interesting to know how many users would vote with their feet based on this point.
Trying to "solve" this multiple identity problem is complex both from a personal as well as a technical perspective.
I suspect most people neither want nor need this additional complexity.
The people who really "need" it (i.e. those who are irresponsible maniacs but do not wish to appear as such) would not really benefit from it anyway. The thing about irresponsible maniacs is that if you sit down and talk to them for an hour (the typical duration of a corporate job interview) you can detect that either they are a maniac or that they have something to hide. Either way it's a no-hire. There is no need to dig through Facebook or Google to detect this sort of personality.
Many people already "solve" it by maintaining different accounts on different social networks. I use LiveJournal for keeping up with my HP fandom friends, planWorld for my Amherst friends, FaceBook for high school friends, and I've switched between C2/L:tU/Reddit/News.YC for programming/professional acquaintances. My identity in each is recognizable, but subtly different, since I'm writing for different audiences.
There's some cross-talk - many of my younger HP fandom friends found me on FaceBook, one of my Amherst friends found me on Reddit, and one of my middle school (!) friends found me on C2. But social relationships are sustained by groups, not individuals, so even if they find me they tend to lose interest in what I'm doing.
Using different services/accounts to narrowcast specific segments of your life to specific groups of people is a traditional use of social networking tools.
But this story is not about using social networking tools in traditional ways. The author is positing an emergence of new uses of social networking tools based on the reputations of the individuals within the network. If FB or some other service manages to be both big and a true business ecosystem new forms of business will emerge based on the reputations of the individuals within the network. These forms of business have the potential to attract a much larger segment of society to the social networks.
My point is that within the context of such a reputation-based, socially-oriented, business-friendly ecosystem people will prefer to have a single identity/reputation to manage. Simplicity will win over complexity when "typical people" are involved. And the ultimate winner will cater well to typical people rather than technical people or the users of the first N generations of social networking tools.
Trying to "solve" this multiple identity problem is complex both from a personal as well as a technical perspective.
I suspect most people neither want nor need this additional complexity.
The people who really "need" it (i.e. those who are irresponsible maniacs but do not wish to appear as such) would not really benefit from it anyway. The thing about irresponsible maniacs is that if you sit down and talk to them for an hour (the typical duration of a corporate job interview) you can detect that either they are a maniac or that they have something to hide. Either way it's a no-hire. There is no need to dig through Facebook or Google to detect this sort of personality.