Symphony.

See code sample here:

http://www.getsymphony.com/discuss/thread/21946/2/#position-33

When underscores are within a word, such as jitimagemanipulation, Markdown thinks the middle word “image” is italics. When naming conventions for S2 are so strict, it’s annoying Markdown can’t handle it.

Github have implemented their own Markdown flavour which as indeed been adopted by other major sites (Stack Overflow one example):

http://github.github.com/github-flavored-markdown/

The three differences:

• remove support for intra-word underscores
• auto-link http://…
• retain single line breaks (removes the two-space rule)

How about using this on the Symphony site? Perhaps this could easily be added to the Markdown Text Formatter extension — a Markdown (Github Flavour) option.