I think sharing here would be a better solution! :)
I'm actually looking forward to the cookie sync... I customized the WP plugin (jl-punbb) to not sync my "unverified" account (that I have since I'm using Register Plus, a plugin that allows me to have a user click a link on a welcome email, to confirm his address before "activating" the account) and I'm in the process of writing a cronjob to sync the DB, pushing new, confirmed, users from WP to punBB every 10-20m...
But I'm not sure about the cookies... I've never worked with them so I'm not sure what could use some work in order to function properly! I definitely need the sync because I'm gonna disable all member related functionalities from the punBB side of things...
I'm also curious on how I can call WP functions (like verify if the user is logged in before giving access to the forums even) and how to integrate the header/footer of the site... :)
Any help would be appreciated :)
EDIT: Using WP2.7 RC1 (final coming out next week) and PunBB 1.3.1!