Does your company need social marketing? Is it just something you have to do because everyone else is jumping in the well? Most B2C companies do need to get on the bandwagon, but B2B companies need to evaluate their strategies before you jump. Perhaps if your product would benefit from a facebook or twitter presence; if you want to build up a public opinion; if you are going for an IPO, or some other valid reason; than it might make sense.
Everything starts with an objective; what do you want to achieve. Do you want a group page - a controlled community interface but the updates don't appear on the member feed, or do you want a fan page where your status updates appear in fan feed home pages?
Another thing to note is that please don't use your personal facebook id to create company groups/ pages as facebook currently has NO option to delete the original creator. So even if you leave your job, you would be stuck with being a creator and worse, the earlier company would be stuck with you. Create a company ID and than create Group pages etc.
More on this later...