Amazon reportedly is close to launching its own app store for the Android mobile phone operating system. Details are sketchy still, but according to TechCrunch, essentially the program asks developers to create apps for the Amazon-branded app marketplace that will run only on Amazon-approved Android devices. Amazon would approve all apps and take a 30% cut of any sales.

It would be similar to Verizon’s planned app store as it would run on the Android platform and exist separate from the official Android App Market, making it somewhat of a competitor in practice if not in name. Details are still slim, though, so it’s possible Google and Amazon may be working in tandem on it which would give Google some much-needed benefits.

Primarily, that includes a direct billing relationship with Amazon’s millions of customers, all of whom have credit card information stored in Amazon accounts. One of the biggest challenges to the Android Market is that it requires a Google Checkout account, but there are far less of those accounts than Android accounts.

It could also play an interesting role in whatever Google has planned for its music service. Amazon is the perennial No. 2 in the digital download market, far behind Apple, but at least it has an a la carte service already up and running. Blending that into Google’s planned cloud-based locker service would make far more sense than Google trying to build one of its own. And Amazon already has a mobile app created for Android devices that provides for mobile buying and downloading of tracks.

And, finally, a Google-Amazon tie-up would solve much of Google’s retailing woes. Google has been challenged so sell really much of anything to consumers, be it services or hardware. The Nexus One phone was a particularly spectacular example of how poorly Google is situated as a retailer. Amazon of course does not have that problem.