Thanks to Andy Rowell for pointing out that Dale Allison's Clark Lectures, recently given at Duke University, are now available online at Duke's iTunes U site:
2008 Kenneth W. Clark Lectures Online
Unfortunately, the link on that page takes one to some kind of iTunes thing. For those of us who don't use iTunes, I will inquire about an alternative link.
Update (16 June 2009): Now I do use iTunes and have my own podcast on iTunes U and I notice that the old link above on the Divinity School site had disappeared, so I have refreshed this post, and added a new Duke iTunes U tag.