The old year has ended so it's time to look back at what happened in the world of mobile gaming during 2009.

Equally, the lessons of history are useless without a future to demonstration what we've learnt, so as well as asking various notables about their view on the past 12 months, we're also getting them to look ahead to 2010.

You can see the full list of our end of year interviews here.

Mobile advertising proved to be a key revenue stream for many iPhone developers during 2009, especially as the prices for paid games collapsed. Mobile advertising network GreyStripe provided an opportunity to hook into the market, with monthly revenues of over $10,000 claimed for some titles.

Michael Chang is its CEO.

Pocket Gamer: What was the most significant event of 2009?

Michael Chang: To pinpoint any one event in 2009 would understate the significance of the year as a whole for the entire mobile game - or mobile content industry for that matter.

Since the peak of the industry marked by the sale of JAMDAT to EA at the end of 2005, the mobile game industry was marked for dead with slow growth and tight carrier control. Throughout 2009, the industry did a 180 and we saw the emergence of thousands of independent developers bring unparalleled creative energy to what was once a slow moving and lumbering industry. Many of these companies are flourishing and are profitable.

What was the most significant event for GreyStripe?

2009 was a hugely validating year for the ad-supported app model that Greystripe pioneered with our launch of the first ad-supported Electronic Arts title, Lemonade Tycoon, and the first Real Networks titles Track and Field and Twilight: The Movie Game.

We aren't only working with the Tier A publishers though, but a long list of thousands of fantastic developers in every category. Having NBC Universal invest in us wasn't too bad either!

What was your favourite mobile game of 2009?

That's a tough one. There are so many great titles. I am addicted to WordWarp by MobilityWare because it is simple and has endless gameplay. A Greystripe favourite was one that we developed for an advertiser - Axe's Pogo Xtreme.

Other favourite games around the office this year were Lemonade Tycoon, Sheep Launcher, Words Free and Tower Madness. All of these are great examples of apps that were successfully monetised with ads.

What do you predict will be the most important trends in 2010?

Without a doubt, digital convergence will be the biggest trend for mobile gaming in 2010. This is the convergence of mobile and online user experiences, whether it's playing the same game across multiple devices or seeing the same ad campaign through both online and mobile media.

At the highest level this is an important trend because the money is where the audience is. As a developer, your audience expects you to be everywhere they are, and as an advertiser, they expect to be able to reach an audience through every platform.

On the developer side, Digital Chocolate is a great example of a company doing this extremely well.

If you could enforce one New Year's resolution, what would it be?

It would be to make sure that developers keep monetising their content through multiple revenue streams - for-pay and advertising.

Multiple revenue streams is what every major media company is talking about right now to maintain a healthy business, and mobile will not be left out.

Thanks to Michael for his time.

You can keep in touch with Greystripe's activity via its website or Twitter.