Great article here discussing the lack of mashups inside the enterprise, and comparisons of mashups to old-world spreadsheets as a tool of empowerment for the end user.

With or without the listed challenges resolved, we seem poised for rapid acceleration of mashups as REST APIs and “web sites as web services” concepts grow.  A real goal should be to implement services inside the enterprise to foster internal mashups.

The 10 top challenges facing enterprise mashups