I recently came across a blog post from Celent, a research and advisory firm for Financial Institutions. Jacob Jegher, a Senior Analyst, recently released a report entitled "Demystifying Social Media and Next-Generation Online Banking". While we are not subscribers to Celent research (we work with a very modest publication budget), the extract seems to hit all the points I've found in our social media efforts.
I take it as a good sign that a traditional research firm like Celent is advocating participation in social media for financial institutions. We've embraced it and would encourage others too as well. Unfortunately, since I can't see the content, it is impossible for me to say how they suggest banks get involved. If someone has access to the report and can share that with me, I'd love to hear from you.