Wayne Allenmentions our work with combining Vault and NAnt. It's been great to go from idea to code. Eric Sink has made public an access point for the Vault/NAnt code (for a guest account): http://vaultpub.sourcegear.com/.
Update: Along with Wayne's post, to give credit where it's due, Brian Schkerke did most of the initial work, and Wayne's team made some improvements.