I had a meeting with a client and he showed me a recent Chicago Tribune Business section article that praised Facebook and Twitter as lead-generating tools for small business.
He wanted to know how we could implement it for their business.
I then showed him the Facebook link on the home page and how his company already had 12 fans!
He was amazed and very pleased that we were so 'forward thinking' of his business. Of course, I had worked this out with his marketing manager and we had agreed to run a test of a Facebook Fan page and see how it went.
Moral of the story: If its good enough for your client then do it. Don't wait for them to come to you.

If you can, create fan pages and generate some interest. Once its up and running, you can always make the client the admin of their own page and they can manage it themselves.