Hi Dan,
That URL is an RSS XML feed, not an MP3 link. I'm not on a Mac, but think this is the link you want - http://phobos.apple.com/WebObjects/MZStore.woa/wa/viewPodcast?id=268045050
If not, I'm able to get a subscription option in ITunes by going to the ITunes store and searching for "voice of the dba".
Regards,
Abbs