I have 3 game libraries installed on my PC: pyglet, pygame and Panda3D.
I would like to create a 2D game and make it a web browser game so i can put it on facebook.
I know that Panda3D has a web-browser-plugin. Panda3D is for 3D games mainly.
Therefore, I'm asking, is it possible to play a pyglet or pygame game in a browser? If not, what Python library do you recommend?
Neither pyglet nor pygame will run in a browser. I wouldn't really recommend using Python at all if you target is a web browser. JavaScript (with HTML5 Canvas), Flash, or Java applets are better suited for that environment.
If you're dedicated to the idea of using Python, there are a number of projects that can compile Python into JavaScript. There are some mentioned on the Python wiki. Here are a few:
You'll need to write your own graphics and audio systems, though, since none of those projects can convert the native code needed by pyglet and pygame into JavaScript.