In MrBayes it's possible to generate phylograms that contain nodes with more than two descendants. Such an example arises in the MrBayes manual (see this) for the basic primates.nex.
Question: How should nodes with more than two descendants be interpreted?
Strictly speaking these should be bifurcation trees (i.e. each node has two descendants). My guess is that two speciation events occurred so closely together that MrBayes is unable to accurately determine which occurred first. If that is correct, I'd then appreciate a pointer to a document that can confirm this guess.