That takes no work. However, what if you want a colored background? You get something like this:
Yuck. Thankfully, PowerPoint 2013 makes it easy to set that background as transparent. First, click on the image. When it is selected, Picture Tools will be available on the toolbar at the top. Then choose Color and Set Transparent Color.
|Sorry for the bad annotation - I wish the snipping tool had built in arrows and shapes.|
Your cursor will then turn into a color picker. Click on the color you want to be transparent - in my case, the white background of the map - and voila!
Pretty cool, huh? Much easier than Photoshop.