You may also be interested in a project I started about six months ago, which is a fork of IanniX I call GeoSonix. It will be free and open source. In a week or two it will be available as an alpha download of the source or executables on Bitbucket. At this point only OSX and Windows because I haven't had time to build and test a Linux version.
The name GeoSonix comes from a combination of IanniX and GeoMaestro: http://www.zogotounga.net/GM/eGM0.html which is/was based on Keykit, and is my other source of inspiration in the project.
Here's an example of what GeoSonix can do: http://vimeo.com/36209199 There are more examples on my Vimeo account.
I actually contributed the code for many of the enhancements in the most recent version of IanniX and wrote the updated documentation.
However I reluctantly forked it because I wanted to make more of a fresh start than the IanniX team would have wanted (its a long story).
I initially focussed on the user interface, making it easier to use, and on bug fixing, making it more robust. Since then I've added lots of other cool features and have more planned. For example:
with resource forks like in Ableton Live
different system setups, and to be routed to different sound generators
parameters rather than requiring all commands to be converted to strings.
understand and easier to move forward, and fixed lots of bugs.
GeoSonix has probably 50 significant enhancements over the most recent version of IanniX.
If you're interested, I'll post here again when GeoSonix is available for download.