The odds of all this working are about 50:1 and it's taken what seems like (and probably is) days to learn about it, subscribe to all the various websites with their individual user names and passwords - OpenID notwithstanding. I know I'm verging on geriatric at 50, but I like to imagine that even the highly netted-up younger turks of my acquaintance like Mike Butcher, Thomas Power and Mitch Joel have their moments of overwhelm. There must be a great business out there for somebody who can integrate all this stuff and either configure or manage it for clients.
Meanwhile the main trade-off still seems to be between simplicity (one easy-to-remember username and password on all sites, with full auto-completion) and security (a different, secure name and password on every site, manually typed in every time). For most people the latter must involve buying and diligently using a secure database for all those passwords (I use a great little app called SplashID which syncs between my Mac and iPhone) - but these databases can presumably be hacked... not to mention the investment of time in retrieving the passwords and, even more annoyingly, finding that this website is yet another one you forgot to enter into the database and having to open a duplicate acccount! I suspect millions are choosing simplicity over security.
And then there's good old-fashioned privacy. I saw a talk at TED 2008 about the future of social networking. It was pretty scary. At the end I asked: "What about privacy?". The answer was: "Forget it - your children have already left it behind." While those over 30 agonise about what to post on Facebook v LinkedIn, what to tweet and who is a real friend, the teenagers are already out there sharing everything. Maybe it's the end of masks and role playing, and the dawn of a new, integrated and wholly honest age. Or maybe they will all get badly burned and find new ways to silo their personae online. Being British and my age I still value privacy, which is one reason why I react against the audio pollution in train carriages, where I receive all sorts of personal information I don't want about my fellow travellers as they rabit away on their mobiles, seemingly oblivious to the existence of those around them. The other day a man paid his builder in just such a carriage, reading his credit card details out for all to hear. Maybe privacy is indeed a dying value. I for one will mourn its passing.