Omnia is a consortium of open-source software for computational biophysics and chemistry.
To install, you just need a working python / conda installation (see http://docs.continuum.io/anaconda/install.html) and the following commands:
conda config --add channels http://conda.binstar.org/omnia conda install omnia
This will add our omnia binstar channel to your conda repositories and then install the omnia metapackage (https://github.com/omnia-md/conda-recipes/blob/master/omnia/meta.yaml), which current includes OpenMM, MSMBuilder, MDTraj, and PDBFixer.
Note: currently only python2.7 on OSX / Linux are supported, but python3.4 will be supported in the coming months. However, individual components of omnia (such as openmm) may be available for your platform. You can install the components individually via the following commands:
conda config --add channels http://conda.binstar.org/omnia conda install openmm
A list of packages and versions available for your operating system is available on binstar: https://binstar.org/omnia/ For example, the openmm packages available are shown here: https://binstar.org/omnia/openmm/files