The user list is for discussing installation and configuration issues, as well as 1394 devices and the software required to make them useful. The developer list is to discuss code issues if you need to write a protocol driver, use the libraw1394 API, or need the low level drivers or subsystem to support something new.
Some users monitor both the user and developer list.
You can find archives and subscribe to the lists on the project's mailing lists page on SourceForge.