Linux version (still tracker only) now works on Ubuntu, Mint, CentOS, RedHat, Debian and Arch Linux.
ManicTime Server also works on Linux, so while still not ideal, you can run ManicTime Server (for UI) and Linux tracker both on Linux.
Please compile for Redhat/Centos too! The current .deb file works only under Debian/Ubuntu.
Port manictime to Qt, will be able to run on loads of platforms!