You may find that there is quite a bit of crossover between customer support and marketing. For example, it remains the responsibility of both to monitor the social networks for your brand/product mentions, for new opportunities, and to respond to the needs and questions of your customers. However, as a member of your marketing department, your responsibilities will go quite a bit beyond that.
Assuming that you have been charged with creating buzz for your small business via social media campaigns, you are actively encouraging others to engage with your business on these same channels. You are looking for shares, comments, retweets, replies, likes, and +1s. When you receive those, and you will, it is critical that you be prepared to respond in kind with a thank you, a follow-up question, or whatever it takes to drive the conversation and the relationship forward. If you find you have an interest in your company's services, create a task...