Millennial Media has created a Scorecard for Mobile Advertising Reach and Targeting (SMART), a snapshot of monthly mobile advertising campaign data.

After registering for the scorecard, brand advertisers are privy to key metrics observed through the mobile ad network’s campaign and network traffic, such as targeting and handset information. As the scorecard is advertiser-focused rather than publisher-focused, it uses metrics like reach and engagement vs. "size" metrics like number of impressions.

The March scorecard, for example, reflected 3.39 billion impressions for the month, and more than 10 billion US impressions in the first quarter - with reach of nearly 31 million out of the 56 million Nielsen-identified mobile internet users.

It also noted that 58% of campaigns use some level of geo-targeting, and 42% utilize frequency capping.

More data from the report:

• The top 20 mobile handsets account for 43% of all mobile web traffic on Millennial Media's networks.
• 10 of the top 20 U.S. mobile DMAs by ad requests were in three states: California, Texas and Florida.
• Average number of ad requests per page view: 1.09
• 42% of brands are utilizing other Third Party tracking capabilities, while 58% rely on Millennial Media for campaign tracking

But the preferred method of measurement is "cost-per-engaged-user," according to Paul Palmieri, Millennial Media CEO.

It's a way for advertisers to gut-check in aggregate across the industry the cost to engage a unique user - and a way for mobile to be compared in aggregate to the value of advertising online or through other mediums, he told Mobile Marketer.

In addition to data, SMART offers analysis and recommendations for advertisers seeking more intelligence on the mobile ad market. The network claims, for example, that mobile provides five times the lift in brand metrics than internet campaigns, based on brand impact studies conducted by market researcher Insight Express.

In addition to the new mobile scorecard, mobile marketers can check AdMob's monthly media metrics report and the Crisp Wireless Index.