Social network aggregation

It would be really cool if there were only one social network to belong to, with the possiblity to tag the kind of relationship to the contacts one has. This is why we now have social network aggregators, which is a good idea to begin with. However, if we think about the content our contacts produce, of which not all would be relevant, given a specific context, I start to think that some intelligent filtering on top of contact aggregation would be helpful. This might also help discovering new, potentially interesting, contacts relative to what my current concerns are.

Tagging is the first idea that comes to mind, however, as any string of characters can be a tag, I feel that some semantic support is necessary. What I am thinking of is some controlled hierarchy with additional cross-links between terms, so any given term would have potentially several paths to some root node. Nothing new here.

When it comes to some well-defined contribution (e. g. a video about a place, a review of some restaurant), this may be not too difficult to integrate, but how about short utterances, e. g. via twitter? If this utterance contains a link, it might be not too difficult if it is possible to extract the kind of relationship by looking at the destination. But how about if the utterance is just some kind of statement like "I just can't stand the weather", or if one utterance is a follow-up of another?

I would be interested in any kind of thoughts regarding the semantic integration of micro-blogging - feel free to comment or to directly get in touch with me! Thanks in advance.