No, Powerpoint doesn't have a color picker, but I found the coolest little thing. It is a color picker called Color Cop.
It's an exe file that runs on top of what you are doing in Powerpoint.
Download and extract the file
Open the exe while you are running the program you need a color picker in
Drag the eye dropper to the color you want to choose
Color Cop will show you the values of the color
You can now type them in to the custom color values