Medialets, an advertising and analytics startup, bet big on the iPhone early, rolling out its universal SDK at the launch of the App Store two years ago. And the startup just launched a universal SDK that works with the iPad. And the company’s Apple-centric strategy has paid off; Medialets is one of the most widely used ad platforms and counts NPR, CNN and Fox as clients. Today, the startup is moving in a new direction, announcing a Rich Media Ad SDK for the Android platform, allowing publishers and developers to seamlessly switch between ad networks and first-party ad servers.

With the Android SDK, Medialets allows advertisers to create and deliver the mobile specific ads across both Android devices and iPhones. Similar to the universal SDK for iPhone and iPad, the Android SDK will allows publishers to modify and change their ad tags from various networks without having to update their app. As the Android platform continues to grow, more and more mobile ad networks are launching Android specific platforms, making Medialets offering appealing. The SDK works with any first or third party ad sever, network or mediator, including AdMob tags.

As we’ve written in the past, Medialets promises rich media and display advertising on mobile phones that provides deeper engagement with users. In fact, engagement is a primary measurement that the ad platform focuses on when determining the success of its advertising campaigns. But developers and advertisers may be more beholden to click-through rates, which Medialets claim are between 1 and 8 percent. However, eight percent seems a bit high, considering that other rich media mobile ad platforms, including Greystripe and AdMob, are seeing between 1 and 2 percent, in terms of click-through rates.

But Medialets has seen considerable success with its universal SDK offering, most recently striking a deal with The New York Times to use the startup’s rich media ad units for the Times’ iPad app. With the popularity of Medialets’ universal product, I imagine that other mobile ad networks will develop their own universal SDKs in due time.