Pybliographer is available in two flavors:
1.3.x is the current development branch (NOT active at the moment!)
- is more developer-oriented
- has a richer data model and a more flexible architecture
1.2.x is the current stable branch
- mature
- contains a user-oriented GUI
- shipped with most distributions
- but some hard to overcome architecture limitations
Feel free to get the Source_Code, and start hacking, possibly on a task listed in the Roadmap 
Analysis documents
Although they don't reflect accurately the architecture of the current code, here are 3 analysis documents that are worth reading for the background they provide: