You may want to look at the change log here, especially if you installed an older version before.
The development for the version 1.0 is basically frozen. There are several outstanding bugs that can't be fixed due to lack of user feedback: I can't reproduce the bug and I can't make a reasonable guess as to what's causing it, so I need more details from the reporter, but the reporter doesn't provide those details. After a while the bugs will be closed and 1.0 declared finished. In the meantime I'll fix any bugs that are found and reported, provided that I can reproduce them or at least have a good idea about what might be causing them. To some extent I'm also willing to add support for some of the various things that are currently unsupported, if such support is requested and the changes would be small and pretty isolated.
So nothing major is going to follow for a while. However, from time to time you may want to check the MP3 Diags blog, where announcements about new releases are made. Then you can decide based on what changed in a given release if you want to upgrade or not. (If you use an RSS reader, you can add that page to it, so you see the notifications automatically.)
You can also look at change log at the project's site, to see what changed since you installed your version
There are both source files and binaries, for several Linux platforms, as well as for 32bit Windows. More details can be found at the main MP3 Diags download page.