Python is getting pretty big in server side web development and dynamic webpages with the Django which is like Rudy On Rails. It also has a strong presence in scientific software. Another major use is when rapid prototyping is needed or short development time. It also has a pretty good presence in scripting in games.
Really Python can be used for pretty much anything with some exceptions.
I wrote a JSON api for an iOS application using Python and Django. The application performs HTTP requests to Nginx server running the Python/Django backend, the Python ORM queries the database and sends back JSON to the iOS device in the HTTP response. The iOS application than processes the data and creates the views on the application to present to the user.
Took all of a few days to get it working, where if I would have used C++ it would have taken weeks or months.