"Make no mistake about it -- despite the recent buzz around Enterprise 2.0, people have been creating mashups for many years.... Microsoft Excel is arguably the father of the corporate data mashup. For years, Excel end users have cut-and-pasted data to feed their calculation engines. Spreadsheet-based solutions have spread throughout the enterprise without the involvement of IT. Mashup tools enable the automation of this aggregation process, and a new clan of users is poised to run wild with the technology."
-Micheal Ogrinz, from Mashup Patterns: Designs and Example for the Modern Enterprise
As noted in a previous post, Michael warns that mashups could become as unruly as Excel spreadsheets, unless some type of central repository is put in place (dare I say "governance"?) to keep things documented and in check.