There are some great science and technology podcasts out there. A podcast is basically an independent radio show. Unlike radio, however, you can download them and listen when you want to rather than listen to them live. The quality of podcasts varies greatly. Some are very amateurish and some are quite professional.
There are literally thousands of different podcasts out there ranging from audio blogs to professional news shows. Like blogs, some are updated frequently and some almost never.
One more thing before I list my favorites is you don't need an iPod to enjoy podcasts. You can actually use any MP3 player or just listen on your computer (I've heard you can even listen using your TiVo).
Below you will find my favorite Science and Technology podcasts. From most of the sites listed you can download individual programs or subscribe to the podcasts' feeds (more on this in a day or two).
Talk of the Nation - Science Friday
This is actually an NPR weekly radio show hosted by Ira Flatow. You may remember Ira from the PBS show Newton's Apple. Topics range in all areas of science and Ira's guests on the show are the experts in those areas. Each weekly show typically covers at least two major stories (some cover 4-5 stories). Each story can be downloaded separately.
The Naked Scientists Radio Show is broadcast in England. It is an hour long show done once a week that covers a number of stories each week. Each episode has an experiment you can do while listening. I've adapted some of these to use in my own classes.
Science Magazine and Scientific American
Both of these magazines have started releasing podcasts recently. So far they are pretty good, but it's hard to know if they will continue being good or even continue producing new material.
this WEEK in TECH
This week in Tech (TWiT) was started by some of the hosts from TechTV's Screen Savers (before TechTV was bought by G4). It covers big tech stories weekly. It's a lot of fun and has a lot of good information. Through the same site are a variety of other podcasts and video podcasts.