One of the great observations from SMX in Seattle came from Rand Fishkin of SEOmoz. Rand noted that many major brands shy away from Social Media environments because they can't control them. The effect of this is that it creates a great opportunity for smaller players to get high level attention from the market.
This is an important insight as to why smaller businesses should try to move on this as soon as they can, because the opportunity will not last forever. Eventually, the bigger brands will look to move into this space as well. At the very least, this will make the space more crowded, and some of them will do an excellent job of jumping in, and they may well garner a lot of attention.
Even so, the (mostly) open mentality of social media environments does create a long term opportunity for a smaller business as well. But it's a great idea to establish a strong presence now, when the opportunities are large, and the market is open.