I've been meaning to do this for a year, finally caught up with Eric Johnson of Consortio Services to do a podcast. We did about 15 minutes discussing community events, sites, and user groups (please do listen if you want the whole scoop). It was fun, but challenging - felt like I didn't do a good job of being on message and consistent, and I think one of the reasons is no facial clues to help me know when I should cut an answer short or was rambling too much. Think it might be useful if the interviewee could see the interviewer just for that reason, but probably also just means that I need to practice. Same applies to video, I have little experience at being on video and that translates to unpolished delivery at times!
Want to try it to see if it hard or not? Ask my friend Steve Jones to let you write an editorial for the SSC newsletter and then do a podcast to go with it.