What are the responsibilities of the Publication Chair of a conference?

I've been publication chair of an IEEE conference before, and it's pretty straight-forward. IEEE has a well-arranged process for managing conference publications, and you basically just need to hold up your side of the deal and make sure that nothing falls through the cracks.

In particular: you should have an IEEE CPS publications contact. You can get this from the current general chairs, since they're dealing with IEEE, or (since its usually the same from year to year) you can ask the previous publications chair. Set up a meeting with that person ASAP and they can walk you through the process and make plans with you; I've had very good experiences working with their publications personnel.

The key responsibilities that you should expect to fulfill are:

1. Set a schedule acceptable to IEEE and the conference chairs
2. Work with the general chairs to fill out the required forms and get them to the IEEE on time, so that you can get the publications IEEE CPS contract signed. This will include setting the various different types of publications (e.g., main track, short papers, workshop papers, tutorial abstracts, etc), as well as pages sizes, expected number, delivery method (I recommend USB sticks) and budget.
3. Send information about camera ready from IEEE to the various conference chairs that need it (general, program, workshops, tutorial, etc.).
4. Work with chairs to get all of the front matter prepared in a timely fashion and within the schedule negotiated with IEEE (cover, index information, introductions, sponsored material, etc.).
5. Immediately after the conference, report to IEEE whether there were any no-shows (who should have their papers removed).
6. One month after reporting whether there were and no-shows, everything should appear online in IEEE Xplore. If it doesn't, then you need to keep pinging IEEE's representative to make sure things get into IEEE Xplore as promptly as possible.