For me personally, history is a major field of interest. Consequently, history podcast can't be long enough for me, should be in-depth and take me on an extended tour from one podcast episode to the next. I can imagine though, other people may not want to invest long tracks of time into history, yet would like to learn some history as well. For them I'd like to recommend History According to Bob, which has short issues and a long, long list of episodes to choose from. Most of those, however, need to be ordered on CD, as they are no longer in the feed. I'll give two more of those history podcasts, not running too deep, not running too long. (Thanks to the reviews by Historyzine)
The first is the History Podcast by Jason Watt. Not all issues are done by Jason himself, but persistently there is a short monologue about a larger variety of historical subjects. The next is Parnell's History podcast, which in addition to the facts, also delivers some analysis.
These are fine podcasts if you want to get some passing acquaintance in a certain subject. Necessarily there is a disadvantage, the episode can tell the story in a less balanced or less accurate way. This I noticed most profoundly in Parnell's 18 minute delivery of the Israeli-Palestinian conflict, which I know only too well. I guess for many people who know nothing and want no more than a twenty minute historical overview, this must do, but I spotted a number of sentences that in my opinion cannot be said, without error or leading to error. Like suggesting that after the Balfour declaration the British started stimulating Jewish migration into Palestine.