The Astronomy Cast  is a weekly audio webcast program that covers a wide range of space related topics. They now have over 300 half hour programs in their archive. Recently, for example, they had a four part series on the history and future of space stations:

• Ep. 296: Space Stations, Part 1 — Salyut and Skylab
• Ep. 297: Space Stations, Part 2 — Mir
• Ep. 298: Space Stations, Part 3 — International Space Station
• Ep. 299: Space Stations, Part 4 — Future Space Stations