For author interviews, I'll add:
Writers on Writing - they have a whopping number of archived shows as well as current offerings.
Reading and Writing Podcast - not as many offerings, but interesting material.
The Seattle Public Library has
podcasts of author lectures and other activities, including my favorites where librarians get together over coffee to talk about books they've recently read and highly recommend (most are under 2010).
Folks here wonder what use the Sony ereader audio feature might be used for ... well ... stuff like this!