APIs are commonly an afterthought, like a hot tub awkwardly attached to a house - a shoehorned approach that produces a suboptimal app with scarce support that lacks documentation. In effect, APIs are the ugly stepchild of the Web.
He talks about why APIs are commonly an afterthought and some suggestions on how you can change that in your current and future applications. You can listen to this latest episode either by using the in-page player, by downloading the mp3 or by subscribing to their feed. You can also see the slides over on Slideshare.