Steve Rubel has some great conversation on the continuing hot topic of email vs. social network platforms and the future of email. 

If you need something with staying power – something that will last more than a few seconds then email is still the tool of choice. Email is still the work-horse when it comes to driving sales effectively. I absolutely believe in and see the power of multiple social network platforms (I'm here participating in one) but if shelf-life is what you are looking and what you need then nothing beats email.