I don't know that this medium of blogcasting is a thing of the past. Rather I think it has not found a compelling reason to achieve critical mass yet. I think that if some larger players started distributing demanded or highly desired content strictly by podcast you would see it achive the critical momentum necessary to make it a "must use" technology.

maybe if American Idol showed several special segments by podcast.... with 30 million viewers per show in the finals sweeps, that could kick start it.

JMHO