After paying for instacast I haven't been able to sync any of my ESPN Podcasts, I have 3 of them and they are the ones I listen to most. I've tried subscribing right through the app, by using URL, from my iPod... nothing works it never recognizes any new ESPN podcasts.. or old ones either. I've sent several messages to the developer but never got a response.
You're running a BETA Os. 3rd party apps are expected not to work until they release an update. Revert back to ios4 if you need to run 3rd party apps perfectly.