They offer some good reasons for anyone implemented a community driven application to think through the role of profile and identity in your application and what pieces of that information can help the community as a whole.
“In traditional online communities, discussion is the center of the interaction and identity building. Members create relationships (and their own community identities) based on information they post in online discussions. A comparatively small number of all members in any online group choose to actively participate in discussions- most “lurk”. In this situation, the ability for any single member to build an identity hinges upon participation in discussions.
In contrast, social networking enables the creation of identity in the community without participation in discussion. By allowing members to have a personal homepage (instead of a user profile), identities can be built based on the display of the member’s choices of memberships in forums and connections to other people (among other things) on their home page.”
“Social networking enables a new level of community navigation. As discussed previously, members have home pages and displayed on those pages are explicit links to other members and groups. Further, groups display links to members who have joined the group. This sets up an interesting scenario:
I visit Ryan’s Page and see he is a member of the Rock Climbers Forum, so I visit that forum and see Sharon is a member, so I go to Sharon’s page, where I see that she is connected to Jason, who is a member of the Kayakers Forum. I didn’t even know there was a kayakers forum! I love kayaking!”
CommonCraft also links thier comparison of Blogs and web forums: http://www.commoncraft.com/archives/000768.html