We have posted some videos showing what is new in FAST version 4. The first two videos are Chart Dependency and Visualizations.
The Chart Dependency works with Report Builder to allow the user to pick a chart, then all of the other controls, such as Chart of Account codes, will be limited to that specific chart.
The Visualizations allows you to use the new Hyperlink creation to build images into the reporting pages and to use different images based on criteria within the record set.
Both are very powerful features and a welcome addition to FAST Version 4.