As a Podcast is playing, the images, text and web-links can change to reflect the topic. As an example if your podcast talks about marketing techniques then you may want to link your listeners to web-pages or documents related to the current topic. You may simply want to link listeners to your webpage.
This really does reflect the power of Podcasting. Listeners can instantly click on images within the podcast or link to relevant pages.
Since your Podcast will be a reflection of your company and brand then a a carefully thought-out collection of images will be an important factor.