I can confirm a similar issue on 10.04 with Banshee 1.8. I'm using a iPhone 3GS. Banshee appears to sync to the phone just fine and in fact, the podcasts show up under the podcast subcategory on Banshee. When I unplug the phone, the podcasts show up under music and won't play at all as if the files were corrupted. Music syncs and plays just fine. The issue is only with podcasts. Podcasts cannot be deleted through Banshee.
I can confirm a similar issue on 10.04 with Banshee 1.8. I'm using a iPhone 3GS. Banshee appears to sync to the phone just fine and in fact, the podcasts show up under the podcast subcategory on Banshee. When I unplug the phone, the podcasts show up under music and won't play at all as if the files were corrupted. Music syncs and plays just fine. The issue is only with podcasts. Podcasts cannot be deleted through Banshee.