Currently Being ModeratedMay 28, 2012 8:01 AM (in response to Clairefromaz)
I figured out the problem. It's a permissions issue with Lion. My iTunes folder is located on a separate partition and, because of a well-documented bug in Lion (search for "fetching" and "permissions" on these boards to read about the problem), iTunes couldn't store new data (ie, podcasts) on the extra partition. I solved the problem by changing the permissions on the Music folder on the separate partition (made myself the owner and applied the change to all enclosed folders).