I will be the first to admit that I like email much better than facebook and twitter for business.
But here is why you MUST take Twitter and Facebook seriously.
Most people do not go to the time and expense of building a great email list. The email list would be more valuable, but just look at the facts. You really have to know what you are doing to build a good email list, and it takes a long time to develop.
On the other hand, Twitter and Facebook are nothing more than lists and messages that are much more effortless. Many people that would never consider building an email list have large lists of people that get their messages in FaceBookand Twitter.
I am sure the targeting and response of these tools is less effective than a good email list, but look at how things are going. Many people have valuable lists in twitter and facebook and they do not think twice about sharing messages with that list. One the other hand, if I have a great email list, I am going to be very careful about what I share on that list.
Twitter and Facebook may not be as targeted, but they make up for it in size, ease of sharing and viral growth.
To get the most out of Twitter and Facebook, find ways to leverage your relationships there to drive targeted people to your email list and grow that list more aggressively. One is not a replacement for the other, it is just a great tool at the top of your sales funnel.