With the increasing popularity of libraries like jQuery that make Javascript a lot more friendly, I see a tendency to delegate parts of the layouts to the client side: things like coloring of table rows (from simple things up to tools like flexigrid), fixes for cross browser CSS incompatibilities, syntax highlighting and so on.
Is it now an acceptable practice to assume users will have javascript enabled and use the extreme convenience of these libraries or should layouts always be done via markup and style sheets with javascript just for sugar and/or when really necessary?