I was unable to catch Ham Nation live last night (sorry, I was watching the Reds). An in-depth look on iTunes and even TWiT's website revealed no subscribe link (but they DO have the audio posted). So, with a little digging, I found the address: http://leoville.tv/podcasts/hn.xml.
To subscribe in iTunes:
1. Open iTunes
2. Go to Advanced and then to Subscribe to Podcast...
3. In the Address window, paste the link (above)
Update: want video?
Large size: http://feeds.twit.tv/hn_video_large
Small size: http://feeds.twit.tv/hn_video_small