Just over four months after introducing them, Twitter now gets the lion's share of its daily revenue from mobile ads, with 60 percent of its monthly users accessing the service through mobile devices. A new report in The Wall Street Journal describes how the ads are paying off for companies like the restaurant chain P.F. Chang's, which used the platform for a Chinese New Year promotion earlier this year. Tying the ads to appropriate search terms, the company received roughly 700,000 hits in four days from mobile devices, with just 300,000 coming from the desktop.

The key, it seems, is timeliness, one of Twitter's core strengths. When Chang's tried to replicate its success with a series of ads about lunch offerings, the results were much less impressive, lacking the "occasional" element of the Chinese New Year campaign.

The news follows a series of positive reports earlier this month on Facebook's mobile ads, helping to pull the beleaguered social network out of its post-IPO slump. With Facebook now reportedly working on location-based advertising, Twitter may still need to up its targeting game to compete for a limited pool of mobile ad dollars. Last month, CEO Dick Costolo boasted that Twitter was doing "delightfully well" in mobile revenues, but these things have a habit of changing remarkably quickly.