For best possible front end performance jQuery should supporting defered/bottom of page loading of jQuery somehow.

Bellow is a simple proposal, idea is to provide a small official seed function of jQuery so scripts that use jQuery(function(){}) will work like before, and when jQuery is loaded add functions registered on it to internal list of functions to execute on document ready.

Something like:

var jQuery = function( fn )
{
    if ( Object.prototype.toString.call( fn ) != '[object Function]' )
        throw "jQuery seed error, supports only functions, not: '" + fn + "'";
    jQuery.readyList.push( fn );
};
jQuery.readyList = [];

And then in the full jQuery implementation, check if _jQuery is defined, and set to internal readyList if readyList is defined as a property.