Microsoft has relatively quielty released a new version of Bing for the iPhone. It adds a range of features and capabilities, as well as improving some existing features. Bing on the iPhone was already a very strong app and now it has a lot more to offer.

Among the list of things that are new:

• Barcode (and cover art) scanning with the iPhone's camera
• Bing Social integration with Twitter and Facebook. It offers search results from your social network and alternatively becomes a Facebook and Twitter client
• More movie clips and trailers
• Improved shopping/product results with "reviews, ratings, and prices" (accessible via the barcode scanning as well)

The barcode scanner, like others in the market, makes it possible to quickly check prices and product reviews in the store without typing in product names or other identifiers. The social features are also fun/useful. You can search on a product or place and see if your friends have said anything about it.

The Bing iPhone app is underappreciated in my view. It's quite a bit richer and more user-friendly, for example, than the comparable Google app for the iPhone. Google offers many of the same capabilities spread out across Maps, Product Search and Goggles however.

These new Bing upgrades have made it more useful in my opinion. Beyond this, though not new, it has very good voice search. At some point soon, I'm going to do a quick "head to head" comparison of Vlingo, Nuance, Bing and Google voice search results.

This is just a quick overview. There's more on the new Bing iPhone app at Search Engine Land.