One thing that I find confusing about multilevel approaches is that at times it seems to suggest that some variables influence the DV indirectly through their impact on the group which then influences the first level DV. This is particularly obvious in say Raudenbush and Bryk who my training in HLM was based on. They have separate equations for 2nd and above level units (like school or hospital). Its true that they have an overall equation that combines these higher level equations eventually into an overall model, but at least in my classes that did not get a lot of emphasis