Namespace Pattern #3 (82 chars)

vanilla-namespace-3.js

//namespace patter #3 - with comments
this.n = function(s, array, lastItem) {
    if (array) n(s[array = lastItem.shift()] = s[array] || {}, array, lastItem);
    else if (!lastItem) n(this, 1, s.split('.'));
}

//namespace patter #3 - obfuscated (82 chars)
this.n=function(a,b,c){b?n(a[b=c.shift()]=a[b]||{},b,c):c||n(this,1,a.split("."))}

//namespace patter #3 - usage
n("system.drawing");
system.drawing.doIt = function(){};
n("system.net");
system.net.constant = "const";

console.log(system.drawing.doIt);
console.log(system.net.constant);