I'm waiting to see if Wugfresh gets it linked, I use his for my 7 and 10...
Just a few days after release of the Nexus 9, and this XDA developer (Chainfire) has already figured out how to root it.
Nexus 9 Android 5.0 Update: How To Root New Google Tablet Running Latest OS [TUTORIAL]
I'm waiting to see if Wugfresh gets it linked, I use his for my 7 and 10...