Open Social is definitely on my radar, though to some extent I think the social web stuff is mostly time wasting applications like silly vampire games. I do think getting all contacts syncronized across different sites is useful and some of the activity stream stuff is ok, but mostly what people do on Facebook, MySpace, etc is waste time and I think the next bubble will be because we wasted a lot of time developing time wasting apps. LinkedIn and Plaxo are more moderate and don't have as many time wasting things but apparently people love to waste time and therefore Facebook and MySpace are more popular and now all these venture cap folks are putting a lot of effort into helping people waste their time more effectively. Sooner or later that bubble will pop.
But people do want to build social sites with mojoPortal and it poses some challenges. Currently if a user has permission to create pages and put features on them, that user is generally been given a good deal of trust and is considered a trusted user. But in social sites its like they want anyone who registered to be able to create pages and add content under their own little node of the site. So in this case there is no particular reason to trust these users and yet we still want to grant them the power to create pages and put features on them as if we trusted them. And they want all the bells and whistles like Flash and Video. So to support this kind of site I think we do need more ways to limit the possible damage. Caja, looks like a possible solution, thanks for that as I had not seen it before. I suppose we can also implement specific widgets for things like YouTube or use Open Social, but it seems like no matter what we do there is still a good deal of remaining risk from pulling in rich content from external sources. I think that a lot of organized cyber criminals are making MySpce their playground because it affords so many opportunities for deploying malware and gathering information that can be used in identity theft.
Anyway, I'm ranting, I'll stop now 