David Meerman Scott made this excellent point in a long post about social media and companies:

I think the big thing here is trust. The reasons cited above are just an excuse. If you trust your employees, they might surprise you. But if you don't trust them, over time you end up with only the corporate dregs who don't mind working in an organization that won't let them communicate with others in the ways that people are using today, like Facebook, YouTube and the like.

Very, very true. Rather than have lots of rules, try trusting your staff, and having guidelines. Then, have your management actually make decisions when there are problems. I know, I know - there's a huge fear of those "decision things" at many companies. You know what though? Those companies are dead already - they just don't know it yet.