Mashups are gaining power. We already have a dozen Mashups in our public mashups library. If you have TargetProcess On-Site or Free edition, you can freely download and use all the mashups. On-Demand mashups are on the way.
Here is an example of REST API and Mashups usage to create a nice report. This report is available in Reports section in TargetProcess and shows how many user stories were implemented for a particular month, for all the projects.
You can see which projects are loaded and which projects are on hold, in an instant.
You can select Bugs, Issues and Features as well. Here is a zoom-in on this report.