I installed the NodeJS plugin and set up a few installations.
In my NodeJS 0.10.33 installation, I set it to globally npm@latest and grunt-cli
This worked great for 72 hours, then broke all our builds when it attempted to refresh, not the instances under $JENKINS_HOME/tools/jenkins.plugins.nodejs.tools.NodeJSInstallation/NodeJS_0.10.33_npm_latest/bin/npm, but /usr/bin:

{{"/var/lib/jenkins/tools/jenkins.plugins.nodejs.tools.NodeJSInstallation/NodeJS_0.10.33_npm_latest/bin/npm" "install" "-g" "npm@latest" "grunt-cli"
npm ERR! node v0.10.33
npm ERR! npm v2.12.0
npm ERR! path /usr/bin/grunt
npm ERR! code EACCES
npm ERR! errno 3

npm ERR! Error: EACCES, unlink '/usr/bin/grunt'
npm ERR!

{ [Error: EACCES, unlink '/usr/bin/grunt'] errno: 3, code: 'EACCES', path: '/usr/bin/grunt' }

npm ERR!
npm ERR! Please try running this command again as root/Administrator.

/var/lib/jenkins/tools/jenkins.plugins.nodejs.tools.NodeJSInstallation/NodeJS_0.10.33_npm_latest/bin/npm install -g npm@latest
npm ERR! Linux 3.13.0-46-generic
npm ERR! argv "node" "/var/lib/jenkins/tools/jenkins.plugins.nodejs.tools.NodeJSInstallation/NodeJS_0.10.33_npm_latest/bin/npm" "install" "-g" "npm@latest"
npm ERR! node v0.10.33
npm ERR! npm v2.12.0
npm ERR! path /usr/bin/npm
npm ERR! code EACCES
npm ERR! errno 3

npm ERR! Error: EACCES, unlink '/usr/bin/npm'
npm ERR!

{ [Error: EACCES, unlink '/usr/bin/npm'] errno: 3, code: 'EACCES', path: '/usr/bin/npm' }

}}