If you’ve never heard of LaTeX before, you’re not alone. LaTeX is a markup language for typesetting, and is often used to write formulae so that they show up properly.
Here’s the wikipedia article, with cool tutorials and references listed: http://en.wikipedia.org/wiki/LaTeX
LaTeX parsing is enabled by default, but it’s in prefs if you’d rather turn it off. Any LaTeX is enclosed in “{$ ” and ” $}” to signify it’s LaTeX.
For example, you could write “blauegh! Formula should be {$ f(x)=\int_{-\infty}^xe^{-t^2}dt $} and NOT {$ f(x)=\int_{-\infty}^xe^{-t^2000}dt $} silly!“
And here’s an example of how it shows up in Mibbit.
For some, this will be completely irrelevant, but it seems a useful thing to have in a visual webchat client
-> 
* You can now change the colors of the text, and links that show up in input menus such as [Translation] [Pastebin] etc. Checkout [Prefs]->[Chat input].