The open beta version of PS Suite SDK incorporates a 2D graphics game engine and 2D physical engine, as well as a variety of content samples which utilize these libraries, in order to help developers create content that is optimized for portable devices.
And indeed, several online music stores that have the makings of a site as useful as Amazon's have had trouble getting record companies' permission to offer album samples, and their prices are typically little lower than those of physical music stores.