In case you missed it, iTunes is now insisting your podcast artwork is 1400 x 1400 pixels.
iTunes prefers square .jpg images that are at least 1400 x 1400 pixels, which is different than what is specified for the standard RSS image tag. In order for a podcast to be eligible for an iTunes Store feature, the accompanying image must be at least 1400 x 1400 pixels.”
The key line here, apart from the image specs, is “In order for a podcast to be eligible for an iTunes Store feature, the accompanying image must be at least 1400 x 1400 pixels”.
Do not underestimate the significance of this because you want your show to appear in the New & Noteworthy category; iTunes’ New & Noteworthy can send you a stack of traffic.
Apple periodically updates the podcasts they’re showcasing in this section and it’s essential you give yourself a shot of appearing here.