Is there an interactive graphing library for python

Looks like Nodebox might be what you want:

http://nodebox.net/code/index.php/Graph Mac OSX

http://www.cityinabottle.org/nodebox/ Windows (using OpenGL)

The graph object has functionality for mouse interaction as well, bundled
in the graph.events object. It has the
following properties:

• graph.events.hovered: None or the node over which the mouse hovers.
• graph.events.pressed: None or the node on which the mouse is
  pressing down.
• graph.events.dragged: None or the node being dragged.
• graph.events.clicked: None or the last node clicked.
• graph.events.popup: when True, will display a popup window over the
  hovered node.

Also came accross Gephi, looks like that might have the functionality you want as well.

http://gephi.org/ Windows, Linux and Mac OSX

Gephi is an interactive visualization
and exploration platform for all kinds
of networks and complex systems,
dynamic and hierarchical graphs.