For example, if you search for "Shazam," rather than simply provide results about the app, Google will push links to the application itself to the top of the results pile. For the iPhone, that means links to the iTunes App Store. For Android, that means links to both the Android Market, and third-party sites for direct downloads.
This new search feature is especially helpful for the latter situation. I've often performed searches for apps and been unable to locate the download link. Having fast(er) access to the download link will make snagging new apps less frustrating.
Google said this will only apply to searches conducted from Google.com. Searches conducted from the dedicated search apps for both iPhone and Android will return normal results that don't place a priority on providing links to applications.