Mobile marketing is building momentum because the early adopters are increasingly working out what does and doesn't work in this sector, reports MediaWeek.

The functionality and scale of mobile marketing is coming in line with marketer expectations, resulting in a sudden and dramatic influx of dollars to the medium.

Users, too, are beginning to give mobile ads a second look. Devices have better functionality than they did some years ago, and display ads aren't quite as cumbersome to view, which previously held down acceptance rates. The spate of acquisitions and mergers has also created the sort of scale marketers need to make a significant buy.

Mobile remains a relatively small platform, with just $421 million spent there by marketers in 2006. That figure, however, is expected to reach $4.8 billion by 2011.