Custom shaped corners are available from very first versions of InDesign, but, they were never really improved them till CS5. Now, we can set different diameters and shapes, and for me personally, biggest improvement is ability to modify them Live, without need to go to dialog box!
This cool new feature is called Live Corners, and I think, that was first think I noticed when opened freshly installed CS5 and created text frame. Live Corners feature is represented by yellow box on rectangular objects. Simply by clicking on that little yellow box you enter Live Corner editing mode, which will be represented by little rotated yellow box on every corner. Also, there is cool little Tip (shortcut) that will toggle Live Corner editing mode and that is key 4 (four) (not from numeric-keypad) (this is undocumented feature, but you can find it in keyboard shortcuts under “Object Editing -> Toggle Live Edit Mode”). But, there is so many more that we can do! Let’s take a look! 🙂