We’ve been writing about mobile advertising forecasts for several years at Music Ally, seeing them as relevant to the music industry’s mobile ambitions – even if the emphasis in the last couple of years has been more on mobile as a driver for premium subscriptions to services like Spotify, Deezer and Rhapsody.

Comments at our 2013: A Survival Guide event last week by UMG’s Francis Keeling showed that mobile ads are still very much on that company’s radar as a business model to support music, however.

With that in mind, eMarketer’s latest mobile advertising forecasts are worth a read, even if they’re focused on one country: the US. The analyst claims “US mobile ad spending is growing more quickly than previously expected,” and predicts a 180% rise in spending in 2012 to just over $4bn.

That’s a big revision upwards from the company’s previous estimate, made in September, of $2.6bn of US mobile ad revenues for the year. Which, yes, reminds us that these forecasts tend to be a bit finger-stick-in-windy.

Is music benefitting from this growth? Partly. eMarketer pegs Pandora as the third largest company in terms of US mobile ad revenues for 2012, pulling in $224.8m for the year for a 5.9% share of spending there. eMarketer thinks this will rise to $495.6m of mobile advertising revenues for Pandora in 2014, too.

First place goes to Google – who else? – with $2.2bn of estimated US mobile ad revenues in 2012 for a 56.6% market share. Facebook takes second place with $339.3m / 8.8%, and Twitter fourth with $134.9m / 3.5%. Both social networks launched their first mobile ads this year.

And that’s the thing for 2013 and beyond: how might the music industry tap into Google and Facebook’s mobile advertising networks in particular?

An ad-supported Google Music service remains an intriguing possibility, while Facebook’s reported plans to launch mobile ads outside its own app could be a big opportunity for any Open Graph-connected streaming music service to experiment with a free mobile tier – radio, if not full on-demand.

Interesting times, to say the least.