There are lots of podcasts hosted here, as you can see from surfing the podcast tag or category. You can set it up this way for free by:
1) finding an external host for your mp3 files that allows hotlinking, like Fileden. Then use that link in the blog to provide a download and also to use for the Audio Player below
2) use the WP Audio Player http://en.support.wordpress.com/audio/
3) just write up your notes and put them all in the post with the above.