ulppd is a daemon and postfix policy framework written in perl. It is designed to be fast, scalable, and easy to extend through the creation of Policy modules. It's useful to postfix mail administrators as it provides a simple interface to create arbitrary policy tests in perl. A set of useful Policies is included.
At the time of this writing (version 0.0.7) there are Policies called NDRThwomp, Greylist, SPFCheck, RBLCheck, RelayCheck, and SenderCheck. The non-obvious one in the group "NDRThwomp" implements per-recipient and per-client NDR rate limiting to effectively squash backscatter.
The wiki is the definitive source for documentation. You can also check out the inline documentation in the configuration files, or in the perl modules. POD for the modules is slated for future releases. If you have questions, You may also consult the mailing lists for assistance.
I should hope so; I just made all these up. Also, that wasn't really a question. Anyway, please feel free to ask questions that weren't answered here on the mailing lists.