I would say that this is a bug in Anton's wmd clone except that this problem doesn't happen on math.MO. So I am puzzled.

(Sorry about using capitalization to escape special characters, but I don't have time to fight with markdown on this forum right now.) Edit: I (Anton) edited this post to fix this.

1. in the indented code, dollar signs are converted to <math> and </math>, but left alone in the final output
2. within <pre> tags, stuff between dollar signs is processed, but not in the final output

The existing auto-preview on MO doesn't share these errors. Are you processing the math before Markdown processing? If yes, it would be better to do it after, because that's the way it actually happens (the server does Markdown conversion before jsMath gets to do anything).

I've tweaked the italics/bold function in wmd.js so that it matches the server side implementation almost exactly, so people should now be getting a fairly accurate preview of which math will work properly (e.g. \sum_n a_n is fine) and which math they need to do something about (e.g. f'n=g{n-1} won't work correctly, so you should add some backquotes).

For one thing it doesn't recognize the <latex>math</latex> format, just the $math$ format, but that's an easy fix!

(1) When I entered my answer and was first brought back to the main page for this question, jsmath didn't run, so I just saw the underlying LaTeX code. Reloading didn't help, but going to another page and coming back fixed it.

(2) When previewing this question, jsmath didn't seem to recognize double dollarsigns. That is to say, when I had entered

<latex>\pi^2/6=\sum_{n=1}^{\infty} 1/n^2</latex>

the preview was a textstyle sum, enclosed in a single pair of dollarsigns.

When I went on to enter

<latex>\pi^2/6=\sum_{n=1}^{\infty} 1/n^2</latex>

and

<latex>\pi^4/90=\sum_{n=1}^{\infty} 1/n^4</latex>

the preview showed "and" in italics, with no line breaks. Presumably, jsmath had paired the fourth and fifth dollarsigns with each other.

Can folks (especially those who have "slow" computers that were bogged down with the scriptlet stuff) check

http://math-preview.stackexchange.com/

or more specifically

http://math-preview.stackexchange.com/questions/ask

If that's working out for people, then I won't feel bad about offering the code to mathoverflow.net.

(Note that if you have a slow connection, the page will probably be slow to load at first, as your browser's cache gets filled. Also, if you have a slow internet connection, it is totally worth downloading the jsMath fonts; your browser won't have to download as much stuff to get the math to display)