AH Modding added a comment on a blog entry: WordPress SSO Integration for IP.Board
Blog's been sorted.. was using an old version of IP.Board before the ReCaptcha was hacked - should be patched now.
As for the SSO, yes, you are correct. Users can login to WordPress with their IP.Board accounts, and WordPress will create an account for them.
As for support - it will be supported here: http://community.invisionpower.com/topic/340793-download-wordpress-sso-integration/