To see what was not possible before: try doing contours on a DEM.
1. Put the DEM in a map with Bing streets as a background.
2. In the Transform pane choose the DEM layer and the Tile field, double-click Contours.
3. In the Contours template, choose Full Range and start with some reasonable step of contours, like ever 100 meters for a 0 to 3000 meter terrain elevation set.
4. Press Preview. Fast!
5. Change the Output type from area to line and press Preview again. Fast!
6. Right click on the blue Preview bar at the top of the map window and choose Left or Right. Drag the dividing line back and forth. Fast!
7. While you do all that, you can zoom in/out and pan the map window and the preview doesn't disappear.
8. In the Layers pane click off and on the DEM layer: you can click off the Dem and the preview is still there, showing contour lines over Bing streets.
9. Change your mind about Bing streets? Create a Bing satellite data source and drop that layer into the map. You can do all that and the preview is still there, until you tell it to hide.
There are some more cool things coming. There will be a quick pick to make the preview partially transparent, so you can see things through previewed areas. That's very handy for previewing visibility zones (Viewshed)
In fact, when previewing visibility zones, it's really easy to interactively select some observers and to then with the View from selection only box checked, to see "visible area from any", "visible area from all" and go back and forth, selecting or not selecting some observers, clicking preview again... it makes for a highly interactive and fluid data exploration workflow.
What's wild is you can do all that and still get the preview even if you've hidden the DEM layer in the Layers pane. Try it with the DEM layer hidden and a Bing or Google satellite imagery layer on, and you can see the visibility zones appearing and changing over the satellite layer. For now, if you want to peek underneath you use the Left or Right setting and drag the border to reveal. When transparency is added you'll get that effect too.