Another note on Social Media...
The first rule of social media seems to be that there are no definitive rules. That said, there are a few things that I think you should keep in mind:
1. Commercial interaction HAS to be done on the public's terms. This is completely different than the way most companies are used to promoting themselves -- obtrusively injecting themselves into your life at all times of the day and night. If you manage a company, a brand or a product, take heed and tread lightly.
2. You don't need to say something that is important every time. But you ought to say things that have some value or merit, if only to allow others a peek inside of you (or your company, product or brand).
3. Remember that written words on this "Internet thing" could very well linger until the end of time as we know it. Choose them wisely.
4. Don't meet (or fight) negativity with negativity.
5. And a corollary rule to #4 - refrain from name calling.
Let me know if you have any insights to add.