Depending on how you measure success in the search market, Bing has served Microsoft well in the short time it's been available. Unwilling to rest on their laurels, Redmond is working fast to push Bing even further, doing everything they can to try and wrest some control back from the ubiquitous Google. They're looking at every avenue and platform possible, including the quickly growing mobile market.
To that end, they have identified the iPhone as an area they can improve in, and as such have begun developing
a software wrapper that iPhone app developers can make use of.
The wrapper would let developers easily integrate Bing search results into their applications, likely sorted by the context of the application itself. As an example, someone putting together an application that revolved around finding computer hardware on sale could integrate it with Bing cashback. That's just an example, and clearly Microsoft's intent is to get more eye-time with Bing searches.
The software wrapper is an ideal way to do that, especially since Apple is not a player in the search market. Microsoft truly has only Google to deal with in this, and catering directly to iPhone developers is a clever way to get on the inside of one of the world's most popular mobile computing platforms.