From today’s public filing for Facebook, the following sentence was listed as one of the risks.

We believe that mobile usage of Facebook is critical to maintaining user growth and engagement over the long term, and we are actively seeking to grow mobile usage, although such usage does not currently directly generate any meaningful revenue.

It’s important to note that they currently have 425 million mobile users. Even with the abysmal performance of mobile advertising at .53%-.64% CTR, they could still bring a sizable chunk of change. The real value that the new BigBlue (aka Facebook) will bring, is what I refer to as situational advertising.

Facebook’s big bet on mobile