I concur with Ken Gabriel, This is something akin to a crowded room in which
several discussions are going on at the same time,Similar to the discussions at
the reception during a conference. Would we want anyone to filter those
discussions?My answer:a resounding NO! If someone does no want to join a
particular discussion, he can just walk away.If someone does not want to read a
message, he can just skip or elete it.

Jan Smits,
Assoc.Prof.
Boston University.