Lets face it, from an SEO point of view, clients are generally so behind the curve that they really ought keep shtumm and let us get on with our jobs, all they ever want is a facebook and a twitter, a facebook and a twitter, a facebook and a twitter. Well if that is what they want, why don't they go ahead and do it? But why do you want me to do it? In terms of SEO, facebook is simply rubbish, it gives me nothing [except a real link on my front page to everyone who isn't my 'friend'], and twitter ... you are having a giraffe?
However they do not understand the power of social networking sites, not the huge ones, but there are many which offer us linkers to put links, and good local links, on the internet [for nothing, publicly, etc]. Yet the clients do not want to know, why not ... because the kids all love facebook, but the kids are not likely to 'friend' some rubbish corporate site. Besides the googlebot does not discriminate, you ping it to a public social networking site that you have cleverly linked up and it will, sooner or later [okay, later] come and spider you.
What I simply mean to say is that, Facebook is not the be all and end all of social media, there are a gazillion sites out there, some of whom give you good linkage, others which don't, but most are a whole shit load better than facebook and twitter, but the clients pay the money and they make the choices, so they get the shit results because of their choices.
If you hadn't guessed I love social networking sites, however I use facebook and twitter for what they are good for, that is not SEO.