I recently renamed all sfml packages and dropped the "2" so just remove the "2" from all package name.
libsfml2-dev -> libsfml-dev
python-sfml2 -> python-sfml
sfml2-examples -> sfml-example
The package repository name have also been renamed: use "sonkun/sfml-stable" for stable SFML releases (sfml2-RC included) and "sonkun/sfml-development" for the latest versions (in development).
These repositories contain works based on SFML as well such the Python bindings, sfeMovie, its Python binding and TGUI (v4.2). Soon, they will contain Aurora, Thor and SFGUI libraries.
By the way, what Ubuntu version do you use?
I wanted my Fedora packages ready before announcing this recent change, so I'm sorry to be late on this. :s
Let me know how it goes