After a 9 month hiatus, Facebook is once again launching its mobile ad network, which displays Facebook ads outside of the social network in mobile ads and sites. The goal of the relaunch is to improve the relevancy of the ads over the results from the first test, which resulted in low margins. The delay likely resulted from the combination of low margins and the need to channel money into mobile app install ads and Facebook Exchange, which is driving the ads in the first place. And now that the infrastructure is in place, it looks like the technology is likely here to stay.