Mashups describes how the mixture of data and information from different Web resources is organized to serve a new purpose rather than what it was originally designed for. It is the integration of multiple web applications to create a unified user experience.Mashup is made up from various web apps that are combined, annotated, and aggregated from different sources.

As a business strategy, mashups are very interesting. Mashups can create very effective websites and interfaces, which can help many aspects of business, especially the participatory one. For me one of the most impressive case study is Starbucks. What is a story? When Starbucks announced that they would close a few coffee shops. Now as every coffee lover knows, the first question many had was, “Is my Starbucks on the list?” Within a few hours the Seattle Times published a mashup showing the locations of all the Starbucks closings. The site is not generated by hand or any single program, but is a mashup—two sources combined into one site, that is, an overlay of the list from Starbucks, which was passed on to Google Maps via APIs (Application Program Interfaces). In fact, the mashup first showed all blue rumored closings and then was updated with green confirmed closings. So the map overlay is not only a spatial rendering but also a dynamic temporal display.

More about that read at http://seattletimes.nwsource.com/flatpages/businesstechnology/locationsofstarbucksstoresclosingacrossthenation.html