I\'m new to Grunt. I\'m trying to configure Grunt on my Mac OSX Lion.
I followed the instructions here and then created a project folder that contains the files bel
the key point is finding the right path where your grunt was installed. 
I installed grunt through npm, but my grunt path was /Users/${whoyouare}/.npm-global/lib/node_modules/grunt/bin/grunt. So after I added /Users/${whoyouare}/.npm-global/lib/node_modules/grunt/bin to ~/.bash_profile,and source ~/.bash_profile, It worked.
So the steps are as followings:
1. find the path where your grunt was installed(when you installed grunt, it told you. if you don't remember, you can install it one more time)  
2. vi ~/.bash_profile  
3. export PATH=$PATH:/your/path/where/grunt/was/installed 
4. source ~/.bash_profile 
You can refer http://www.hongkiat.com/blog/grunt-command-not-found/