Audacity, the open-source cross-platform sound editor beloved of podcasters, has released an upgrade to its current version and a beta of a new version:
Audacity 1.2.4 is a new stable version of Audacity, the free audio editor. It includes a couple of bug fixes and minor improvements and is recommended for all users. Audacity 1.3.0 is a beta release that contains hundreds of new features, but this version is unfinished and unstable, and is recommended primarily for advanced users. You can install both Audacity 1.2 and 1.3 simultaneously.
I've used Audacity during the past year for sound recording. Recently, I purchased Adobe Audition 1.5 for Windows which offers significant advanced audio recording and management capabilities as well as comprehensive help and support which you don't get with Audacity.
Nevertheless, if you're thinking about podcasting, Audacity is a great tool to start out with - especially if you're running Mac OS X or Linux - and it's completely free.