Fresh off its monthly SMART report, mobile ad network Millennial Media released a report today that reveals advertiser sentiments towards mobile marketing.

Based on a survey of ad agencies; CPG, Retail, Entertainment, Travel and Restaurant categories are expected to be the top sources of mobile ad spending in 2010. Respondents also reported that “engagement” (a wide-reaching definition) is the number one driver and form of ROI for mobile ad spending. More specifically, “opt in” and list building were named as the most common goals for Q4 mobile ad campaigns.

Other highlights from the report include:

The largest cohorts replied that they will spend less than $100K in mobile advertising in 2009; however, that number jumps significantly in 2010.  With 60% of non-mobile marketers planning to employ mobile advertising in 2010, the increase in mobile spend is among the leading highlights:

• Mobile spending is expected to increase next year, with 31% of agency respondents stating that they will invest between $100K and $249K.
• More than 15% plan to invest more than $1M and 2.6% projected spending of greater than $5M.
• More than ½ of Q4 mobile campaigns will represent between 1% and 10% of their clients’ total spending, but, for a few, that number will be 40%-50%.
• Nearly 75% of the 100 leading agency respondents stated that they have developed mobile campaigns for themselves or a client.
• As an average value, brand respondents forecasted at least a 15 percent increase in spend in 2010.

Mobile advertising performance meets expectations and remains valuable. Among those who have executed mobile campaigns:

• 78% of respondents said the medium met their campaign goals, and an additional 9% said mobile performed “beyond our wildest expectations.”
• For 89% of agencies, the mobile facet of a campaign is just one portion of a multi-platform buy.
• Nearly a third (30%) of agency respondents said mobile has become an “indispensable” part of the media mix. Another 67% ranked mobile as “somewhat valuable” and only 2% said it was not valuable in their overall media mix.

Millennial is a quickly growing ad network and now sits among the top mobile-only ad networks (AdMob and Jumptap). Lots of data are coming out of these networks as they continually release “proof points” to evangelize mobile marketing. AdMob’s monthly reports are another example, though they measure network activity (not survey data).

Millennial separately is making some interesting moves that I’ve recently spent time talking to the company about. More to come on that front.