I've used this technique a few times in classes and everyone loves it! It's not my own but it is really handy and totally easy to do. Check out this page from the “Disney Magic” class in April:
The yellow scalloped border was done using this same technique below. We punched holes in the centers of each scallop using the Crop A Dile for a lace effect.
Corner Rounding Punch from EK Success with removable paper guide (these are green or purple in color).
1. Remove the guide from the punch. It should slip off pretty easily. You can replace it when you're done so keep it in a safe place.
2. Cut a strip of cardstock that you want to be your scalloped border.
3. Slide the strip into the punch. Turn it over so you can see the metal side of the punch (the bottom).
5. Move the strip over so you can see just one edge of the scallop you already punched. Make sure your strip of cardstock is resting on the top of the “V” and punch again. Repeat for the entire length of the strip.
Oh, and I am supposed to be packing but see, I just can't stay away from the scrapping! LOL