There has been a lot of talk about how social media has reached the tipping point and has been accepted as a valid method to market by the so called "early majority." Certainly, I've noticed in my business development discussions that senior marketers have gone from at best ignoring and at worst denigrating social media as a valuable arrow in the marketing quiver to almost demanding that it be included in any PR strategy developed. All in a few months and sometimes the same people!
It's roughly the same pattern I experienced back in the 1990's around the adoption by business of the web itself. First, ignoring, then mockery, then a mad scramble to "get something up!" There were a lot of crap websites developed and a lot of scam "online agencies" that took advantage. Then, as now, early majority type marketers needed to stop, take a breath and think through the purpose of this new medium, how best to use it and when.
Joining the conversation of an active, ongoing community of interest is sometimes a delicate operation, especially for a corporate brand. The potential for mistakes and blowback is there. It's key to work with someone or some PR agency that knows the pitfalls and can be an experienced guide. The fundamentals of PR haven't changed at all: know your audience, figure out the best (respectful and credible) way to communicate and give them compelling, valuable content. Just because your new social media expert follows 20,000 twitters doesn't mean they might not destroy your corporate brand by trampling over the sensibilities of your employee, partner, customer and prospect stakeholders.
EDIT: based on feedback from Mr. Now is Gone (who's a good friend from our college days at AU), let me clarify-- a social media expert with 20,000 Twitter followers is real, undoubted expert. Followers are the key. Someone who is following 20,000 but has few following him is probably a newbie blowhard. If you like newbie blowhards and think they will do wonderful things for your business, have at it. Look at roughly 50-50 mix on Geoff's twitter profile- a nice, large mix of people he follows and people that follow him.