Comment by vain

  function render(tpl,data){
  	var matches = tpl.match(/{[^\}]+}/g);
  	for(var i in matches){
  		var rep =   eval("data."+matches[i].replace('{','').replace('}',''));
  		tpl = tpl.replace(matches[i],rep);
  	}                                     
  	return tpl;
  }
  alert(render("{a} is all that i've {b.a} {b.b} {b.c}", {a:"this", b:{a:"ever",b:"really",c:"needed"} }))

http://pastebin.com/txM6NZBS here, to copy and paste