Is this project dead? Nothing seems to have happened much since 2005. It would be a terrible shame for this project to die, mp3GAIN seems quite popular. In the news section quite a while ago it said that there would be a multi OS GUI which never really seemed to happen. A linux GUI would be greatly appreciated
A Linux GUI is in the works. It's based on wxWidgets so it should be easily portable to other OS'es. Here's the URL: http://mp3gain.cvs.sourceforge.net/mp3gain/mp3gainwx/
It's not feature-complete yet, what it can do is analyze your files but that's pretty much all.
I've been browsing the CVS and the most recent changed date from 6 months back so i really hope the MP3Gainwx project has not been scrapped. If it isn't, then development is at least slow.