The Mobile Marketing Association (MMA), which presides over 600 companies in the mobile marketing space, has published a set of industry ad guidelines (pdf).

Designed to protect customers while encouraging global advertisers to explore the space, the guidelines include the following:

• Recommended aspect ratios are 6:1 (default) and 4:1 (extended)
• Recommended banner widths are 120, 168, 216 and 300 pixels.
• For image banners, animated GIF prevail on most mobile phones
• For SMS messages responding to a customer query, the header should reflect the query which elicited the message

In addition to the guidelines, the MMA also released a white paper called the Mobile Advertising Overview (pdf).

Late last year, the group released a study that found the value of mobile phones increased across age groups as mobile marketing features grow more mainstream. It also published guidelines for mobile marketing to children.