I always like to dogfood new features here on mojoPortal.com to work out any issues, so this site is runnning the very latest code from my sandbox.
A similar issue exists for css files in the skin. We like to organize css into separate files based on logical things from a development perspective, but from a performance perspective we'd like to have only one link to an external css file. I implemented a solution for css files based on some of the techniques I learned from Omar's work. It combines all the css files and minifies them as well using Michael Ash's C# implementation of the YUI Compressor. So far it seems to be working great and I haven't noticed any side effects or problems.
These new feature is only in my sandbox at the moment but will be in svn trunk within a few days.
I managed to get a solution to pin some scripts without breaking xhtml validation, so now on this site I'm testing combined scripts again and so far so good.