I thought I'd bring up this idea again since it might be easy to implement with the new codebase.
If you put text such as [$\int_{x=0}^\infty x^2 dx$] in Wiki, upon saving the article, TeX will be called and translate the formula into an image, and store the image on the server and its name in a database indexed with the formula text. When the Wiki page is presented, the image is inlined (and an alt attribute containg the formula text added). When the page is later edited and saved again, the system first checks whether an up-to-date image of the formula already exists; if not, TeX is called to regenerate it.
This would make mathematicians, computer scientists, physicists and chemists happy. TeX includes a package for typesetting chemical structure formulas and another one for quite general labeled diagrams and trees. There's also a TeX package which allows to typeset musical notes and another one for chess positions.
The concept could be expanded to other programs which can produce graphics on-the-fly based on a textual description. This includes gnuplot (graphs of functions) and maybe packages such as GD, imagemagick or even GIMP.
Axel