itterID X) creates a list Y about subject Z that probably means that X is an expert in subject Z.
It could be interesting to watch someone's lists's tweets - but I am not sure I know how this knowledge can spread. Perhaps I am missing something here. I would be interested in hearing from others.
If you create a list on TweepML, this is different: then others can follow each one of the people on the list and possibly make personal connections.
Apart from lists, the subject of influence and how it can be measured is also interesting.