As you can see from this US PlayStation blog post, users can now link their PSN IDs to the boards. There's a FAQ through there of how to do it. From the site:
Once you've linked your IDs, you'll receive all these great features:
- Identify yourself on the Web using your PLAYSTATION®Network portable ID
- Display your PLAYSTATION®Network portable ID on social networking sites
- Meet other PLAYSTATION®Network members
- See who's who on the PlayStation message boards
- Keep tabs on your PLAYSTATION®Network friends on the Web with the Friend List
Full thing through the link.