Just as 140Proof, an ad network for real-time feeds, hires a new sales VP from Gawker Media, we’ve released a new report on the market opportunities and challenges. Twitter doesn’t want anyone but itself serving ads within the feed, and lately it’s been de-emphasizing what it calls Promoted Tweets in favor of other formats. That leaves tricky issues around sponsored tweets, or targeting feeds on third-party Twitter clients or other platforms. Last fall, I wrote about how to get into the market early. It’s still relatively early in this immature but potentially lucrative segment of social media advertising.