Here's the URL:

http://www.piclab.com/cgi-bin/wiki.pl?Wikipedia_Text_Syntax

A few points to note:

While the document may seem complex because it attempts to be rigorously specified, the final syntax is actually simpler than what we have now. For one thing, ALL HTML is forbidden; the things we use it for now can be replaced by the major new features: table syntax and styles. Half the document describes how we deal with lists, which we are already doing, but which is hard to specify.

Styles, in particular, hide a lot of complexity. With a good toolbox of style classes in the standard stylesheet, users can do a lot of things by simply calling them by name without having to know how they work. This document does not specify how particular stylesheets get attached to particular documents--that too is an implementation detail the user shouldn't have to deal with.

Another simplification is that link syntax is unified: they all use "[[...]]" now, whether external or internal, and all use "|".

I came to agree with those who said that users would expect quote marks for italic and bold to span input lines, so I allowed that, and close them only at the end of paragraphs.

I'm not married to the blockquote thing--it's just a trial baloon, but I think it would be useful.

Note that math equations are now integrated, rather than being an add-on; this is so that styles can be applied to them as well. Also, the "$$" syntax seemed more consistent with the rest of the syntax, and will be familiar to TeXies.

So as I said, this is a vision. I invite comment and criticism. But I think it's important to Wikipedia's future that we do a good job of this.