USD for Maya 0.31 now supports light linking.

Light linking support
USD for Maya 0.31 now supports light linking, giving you more control over the relationships between lights and objects in your scene.
Look though lights
You can now control lighting by looking through a selected light source. You can easily adjust the light's position and direction using standard viewport commands.
Automatic axis and units conversion
You now have the option to automatically convert the axis and unit to be consistent with the Maya system when importing, exporting, or loading a USD stage.
Search for prims in the Outliner
The Outliner now lets you search for prims.
Display Class prims in the Outliner
We've added the option to display Class prims in the Outliner.
Add/Remove Schemas
You can now add schemas to or remove them from prims in the Attribute Editor.
Add Arnold properties to prims
You can now add Arnold properties to prims in the Attribute Editor.
USD cameras support in Render Sequence
Render Sequence now supports USD cameras, enhancing compatibility with USD-based workflows.
See USD for Maya 0.31.0 Release Notes for other improvements and bug fixes.
To upgrade Maya USD, see Installation Instructions.
To get familiar with USD terminology, see USD terminology and composition.
To learn about the USD workflow, watch the tutorials on Maya Learning Channel.
For more information and to get involved with USD development, visit the official Autodesk Maya USD GitHub community.