In a recession, giving away games and content to consumers for free sounds like an appealing prospect. The only problem, if it's funded by advertising, is the fact that ad budgets may be hit by a recession too.

A feature in Advertising Age suggests that mobile advertising is already feeling the strain – a trend which could be bad news for mobile games firms planning to make money from ad-funding their titles.

The article, based on a survey of industry execs, suggests that mobile CPMs (the cost to reach 1,000 consumers) are averaging around $15, compared to $20-25 earlier this year.

That said, there is good news for games firms, with the assertion that games and iPhone apps are commanding a "sizeable share" of the overall mobile advertising inventory.

Meanwhile, the reduction in CPM's is as much about the mobile advertising industry starting to mature.

If companies like Greystripe and its rivals can prove that ads in mobile games deliver a good return on investment, then ad-funded could still become an important revenue stream for this industry in 2009.