The idea seems nice, I'd have to test it out to actually see if it really delivers. One thing that bugs me tho is the tone of the text. It's all "this is the best thing since sliced bread" and "authors surly must be at least demi-gods". This comment in the page's source says it all really:
"headjs :: possibly the most important script after jQuery"
I'm all for cocky and confident attitude, I just think it has no place in a presentational web page/docs