Peter Aiken gave an introduction about what a mashup is by playing "Bootylicious Smells Like Teen Spirit," a well known example of music mashup of Destiny Child's "Bootylicious" and Nirvana's "Smells like Teen Spirit."
Web mashups combine data from multiple sources into a single visual representation. Why is this important to data professionals? Peter pointed out that if we aren't paying attention, this trend could become like XML, where programmers embrace its capabilities, with little regard for the data implications.
Mashups allow programmers to bring data together from various sources into a single service. Someone asked how this relates to Service Oriented Architectures (SOA), and one of the panel members responded that it can be published as a data service. Peter added that this is still evolving.
Dean Allemang talked about using RDFA to build Semantic Mashups. In the early days of the web, there were no links to maps, then came mapquest that could map all. Now you can see all kinds of data on a map, like houses on Craigs list. However, this example has only one data source. On the other hand, an example like Piggybank, a Firefox extension, allows the Firefox browser to be a mashup platform, pulling data from multiple sources to be displayed in a single view. The RDF metadata model provides the ultimate mashup language.