SnapTell, a startup that primarily focuses on image-recognition based mobile marketing, has been acquired by A9.com, Amazon’s search engine technology arm. SnapTell did not disclose the terms of the acquisition.

SnapTell’s visual product search technology lets users take a photo of the cover of any CD, DVD, book, or video game, and the technology will automatically identify the product and find ratings and pricing information online from Google, Amazon, eBay and more. The company has a database of about 5 million+ products. SnapTell launched popular apps for both the iPhone and Android.

SnapTell’s free iPhone app, in particular, was a pretty nifty tool, letting users not only get instant reviews of a product, but also providing local and online price comparisons through TheFind, which allows you to get a quick look at what the item you’ve photographed is going for at local retail stores as well as on online sites like Amazon.

SnapTell has been in the top twenty on the free apps list (which is frankly lower than it probably should be). When we wrote about SnapTell last winter, the company told us that around 35% of its installs see repeated use, and that it has a 15% click-through rate to online stores. Perhaps Amazon will be adding SnapTell’s technology to Amazon Mobile?