Unfortunately, the Apple iPhone does not allow multiple processes to run at the same time. This has been a topic since it's origin. Although this has not been an issue for me since 1.0, now that 3.0 is out and GPS turn by turn directions are becoming available, as well as other dashboard types of applications, this has now become a "possible" hinderence.
But can I run this App at the same time I am listening to a podcast or music? Well I am happy to say you can! Will this translate to the upcoming GPS applications (TomTom) or current app (Gokivo)? I am praying it will. Certainly let me know if you already know!