B.L. Ochman, of Whats Next Online, penned a great piece for BusinessWeek entitled, Debunking Six Social Media Myths. These are all right on. See below for the myths as outlined by Ochman with my own riff on each.
1. Social media is cheap.

Social media is not cheap – particularly if you are a brand with a large Web presence creating a social media marketing program that requires media support, design services, integration, custom UGC components, custom content and etc. This is complicated, time intensive work that can’t be done on the cheap.

2. Anyone can do it.

Not everyone can do this stuff. There are a few media companies, ad agencies and brands out there who really get it. But we’re all learning here.

3. You can make a big splash in a short time.

Marketers should think of their brands as conversations. Conversations don’t recognize the boundaries of campaign dates. Good conversations build over time.

4. You can do it all in-house.

You might be able to get away with doing social media in-house if you’re a small business. But this is certainly not true of large brands. If large brands have any social media presence at all (which they should by now) they need to be talking to experts about how to navigate the space.

5. If you do something great, people will find it.

Well, sometimes, things happen serendipitously. But for the most part, social media marketing programs need to be launched with a full array of media support. Without it you may end up friendless and without engagement.

6. You can’t measure social media marketing results.

It’s tough, but it can be done. Decide on your goals and track from the beginning. FM created the Conversational Marketing Toolbox for just this purpose.