I would appreciate if elog could provide a simple support for mathematical expressions.

A solution similar to wikimedia should be easy to implement and would help a lot.
http://www.mediawiki.org/wiki/Manual:Running_MediaWiki_on_Windows#Alternative_Solution

The idea is to parse the elog entry for a tag (e.g.  <math></math>), extract the code, wrap it into a latex file, and pass this to latex, GhostScript, and ImageMagic. (The latter are already used by Elog, therefore the changes should not be too big.) The resulting image file would then be referenced by the  elog html code.

Of course, the FCKeditor would not support LaTeX. However, the majority of elog-useres should be scientists and rather familiar with LaTeX. Therefore it should be fine if the original LaTeX code is saved (e.g. in the ALT-tag of the image) and the replacement "code to image" is undone for editing.