What economic slowdown? You wouldn’t know it based on the growth in mobile advertising.

Many players in the mobile ad space say things are heating up, rather than melting, and the results of a third-quarter report shows mobile advertising awareness grew 33% in six months while cell phone usage grew at 6%, suggesting an increased allocation of advertising dollars to mobile formats through the first nine months of the year, according to mobile social networking company Limbo and market research firm GfK Technology.

Limbo and GfK released their latest joint Mobile Advertising Report today. The biggest take-away is the continuation of growth that they’re seeing, said Rob Lawson, chief marketing officer and co-founder of Limbo. In the third quarter of 2008, 39% of mobile phone users, or 104 million people, remembered advertising of some format on their phone. “Once you’re past 100 million, it’s a milestone for the industry,” he said.

Beyond that, what type of ads are they seeing? The most commonly recalled ads are those seen in text messages. The mobile Web ad awareness is roughly 50% that of text messaging ads, although it is growing slightly faster.

In terms of the profile of who’s seeing the ads, it’s becoming more reflective of the population over time, he said. Although mobile penetration is highest for younger age groups, 52% of those who recalled seeing mobile ads were aged 35-64, and 28% were 50 and older. Just 43% were under 34.

A slight majority, or 58%, of those recalling mobile ads are male. That may reflect the types of ad campaigns that are created.

Typically in times of a tight economy, ads switch from a branding focus to response-based media, so TV ads might go down but direct mail goes up. The survey did not measure ad spend, but what consumers see. “It  will be interesting to see if mobile is part of the direct group or branding group,” he said. “I think the fourth quarter and first quarter will tell us if the growth is slowed or accelerated,” he said.

Budgets for mobile are generally smaller, and it’s a less advanced medium, so it’s a tough call right now.

Lawson said it’s his guess that most brands use mobile to drive people into a store or get them to take an action rather than change their impression of a brand. Mobile typically is seen as a direct route to consumers.

The Limbo-GfK Technology Mobile Advertising Report is produced quarterly and based on a survey of 1,000 representative American adults and 1,000 U.K. adults interviewed by phone.