@Caroline: actually, Rachel wrote "An organization looking to hire someone to manage social media should not just be looking for a ‘young person’ but rather someone who understands the role social media plays in the marketing puzzle..."
Jeremiah Owyang has often stated that a "social media specialist" or "social media manager" position should, ideally, be a temporary position within an organization. Sufficient cross-training and top-down empowerment of employees in adopting social media tools for business purposes would ultimately negate the need for 1 central individual to hold the title.
To me, "Social Media Managers" are largely tasked with producing relevant online content and figuring out how to incorporate social media into broader communications and marketing goals/campaigns. "Community Managers," as Tim pointed out, are a little more focused on listening and engaging with Friends/Fans/Followers--all while planning how to grow those online communities.