The shape combine function in PowerPoint 2010 is great. Here is an example of how you can create text that seems to be flying through a circle. The key is the create 2 half circles and send one of them to the back. In earlier version of PowerPoint, this was very hard to do. (See a review of PowerPoint 2010 here).

Draw 2 circle shapes

Center them horizontally and vertically

Select the shapes, (inner last), shape subtract

Draw a rectangular shape

Same trick: select them both and do shape subtract

Copy and flip the half moon

Send the right half moon to the back and put some text