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