Eric is a full featured Python and Ruby editor and IDE, written in python. It 
is based on the cross platform Qt gui toolkit, integrating the highly flexible 
Scintilla editor control. It is designed to be usable as everdays' quick and 
dirty editor as well as being usable as a professional project management tool 
integrating many advanced features Python offers the professional coder. eric4 
includes a plugin system, which allows easy extension of the IDE functionality 
with plugins downloadable from the net.

homepage:
http://eric-ide.python-projects.org/