With the Web 2.0 trend and its participation of end-users more and more data and information services are online accessible, such as web sites, Wikis, or web services. So-called mashups---web applications that integrate data from more than one source into an integrated service---can be easily realized using scripting languages. Also, mobile devices are increasingly powerful, have ubiquitous access to the Web and feature local sensors, such as GPS. Thus, mobile applications can adapt to the mobile user's current situation.

We examine how context-aware mashups can be created. One challenge is the provisioning of context data to the mobile application. For this, we discuss different ways to integrate context data, such as the user's position, into web applications. Moreover, we assess different data formats and the overall performance. Finally, we present the Telar Mashup Platform, a client-server solution for location-based mashups for mobile devices such as the Nokia N810 Internet Tablet.