I've added the WBCCI member number and join date to the profiles, and they should be visible when viewing someone's profile and on the left side of posts (such as mine). To enter or update the information, currently you have to go to the Forums profile (i.e., click on the Profile link above, not "Your Account"). I'll add it to the "Your Account" section in the future.
Future updates: I'm thinking about incorporating stars next to the number, one for each 5 years per WBCCI standards, based on the year joined.
In the meantime, enjoy!
This suggestion came from my mom. Who will have several of those stars next to her user name!