I am interested in creating a social network in JBoss Portal, too. Has anyone done that? Perhaps just integrating one of existing social network frameworks (Mugshot etc.)?
Integration with Mugshot would be indeed really nice.
It's open source and Java based so there are a lot of opportunities.
It's still a challenge though, but an interesting one (too bad for me days are only 24hours long :( )
If you are motivated enough, you could check out both codebase and see the possible and necessary integration points (identity comes to mind). I have no clue of MugShot's code...