Update: Standard Markdown has now been renamed to Common Markdown, and the website will be moved elsewhere. Information here.
A team of developers that includes individuals from Berkeley and GitHub has completed a Standard Markdown spec and is looking for testers to help finalise version 1.0.
The project is two years in the making, and came about because Markdown creator John Gruber's original description of the syntax does not specify it in an unambiguous way. This causes difficulties because there are dozens of Markdown implementations and they're not all the same, so documents render differently on different systems. A standard is therefore proposed by the team to resolve this problem.
If you want to assist with this, head over to standardmarkdown.com where you can read the spec and discuss it with other Markdown fans. The team would be particularly pleased if you would implement your own Standard Markdown parser.