Don Park and Robert Scoble both had interesting posts on Orkut over the past week.  In Don's post, he describes a "friendship circle" which could serve as a model on which relationships could be defined in social software.  Robert also described how there should be a way to categorize a person as an acquaintance, or a person that you know but may not be a friend (yet).  I think that these comments really sum up my biggest complaint with social software.  The complaint is that you can't effectively differentiate a lifelong friend with a casual professional acquaintance.  I'd like to see someone do a better job of solving that problem before I'd be willing to invest much more time or energy on networking using one of the social software platforms.