You'll also find sections describing libpqxx, older parts, or mirrors of parts of libpqxx on these sites:

• pgFoundry, the development site for most PostgreSQL add-on projects.
• Launchpad, Canonical's collaborative development application.
• Freshmeat, the online software meta-index.
• Ohloh, a site that tracks software-engineering metrics for free (or open-source) software projects.
• GBorg, the predecessor to pgFoundry that used to host libpqxx development.

There may be more, but these are ones we are aware of and have some involvement with.