Word on the Twittersphere is that BP are now running Facebook Ads stating they are ‘committed to stopping the oil leak’. (do you have a screenshot of one? Please do send it in!)
In this case I wonder though: Engaging on a page is one thing. I get the need for damage control but designing and paying for ads right now is probably going to backlash. Spend the money solving (and then cleaning up) the problem. No matter where BP’s PR guys are there is an audience right now, no need to pay and increase it. There is being upfront and there is self promotion. This is not a time for self promotion.