It would never have crossed my mind to use Podcasts as a form of teaching in schools. I found the pre session reading on this subject a great insight into how such a programme can help with expressing voice, helping with english through letters and reports and developing speaking and listening which is turn aids writing ability.
I realise this type of teaching and learning would be more directed at KS2, however, making links to digital recordings for phonic work or recording a childs authentic voice may help to embed their understanding better.
One potential draw back to using such a programme would be the training involved to teach our teachers/parents about the software. Without substantial training or knowledge in this field then i believe a number of schools would not feel they had the confidence to carry out a sufficient lesson with podcasting.