I'm still a bit new to the whole podcast lark, but since I recently figured out I could plug my MP3 player into my car stereo, I've started catching up with a few on those long business trips.
A sci-fi favourite is Starship Sofa, which I might eventually catch up with. Of interest to readers of this blog might be the show on Religion in Science Fiction. They don't cover much that won't be familiar to, say, regulars at Elliot's blog, but they cover it in a more irreverant style, and with different accents. Oh, and they managed to namecheck a certain blog, so it only seems fair to return the favour anyhow.
Another one that might be of interest is The Sci Phi Show. The main subject here is a philosophical discussion of science fiction, but host Jason Rennie is a Christian, so the occasional religious topic does poke its head above the parapet.
Both of these have forums attached, which I have as yet utterly failed to participate in, but if you have time for that sort of thing, tell them I sent you anyway. ;)
And on the fiction side of science fiction, I have dabbled in Escape Pod a bit, and also Podiobooks has a few titles that sound like they may be of interest to this blog, though I have yet to sample any. I'm expecting to drive to Devon next month (about a 440-mile round trip) - some reviews may well follow thereafter.