LaTeX is use extensively already on the net and in academia to render equations.
A great example of this is wikipedia have a look at this page for 1 example.
http://en.wikipedia.org/wiki/Latitude
I know this is a generlisation but: Using images is a viable way to achieve many things on the web in a browser compatible way - provided you provision for some of the shortcomings. ( eg. Google Maps, Rounded Corners, graphs, advanced typography )
Also 'dated' could be interpreted as 'tried, tested and feature complete'
and thanks for point out sIFR - something i'm going to look at later, i already have a list of things to explore with it, such as printing? ( html + images can do this pretty well, can sIFR?....)