Works just fine in 10.6.8. Yes, it only converts .flv files to .mp3 files, but if that is what you need then this will do the job. Simple drag 'n drop interface, which names the output mp3 after the input flv.
From the developer's site, as well as the readme file that comes with the .dmg file, ver. 0.4.1+ only work on intel machines, and 0.4.2 is only for 10.5+. But it looks like older versions are available at the dev's site if you're still in the PPC paradigm.