We actually have a very basic release of our wiki syntax within the application. If you click on the help icon within the wiki editor you will see it. We have spent some time on improving the documentation in this area, as this is critical for creating wiki documents. You will see this reflected in the upcoming release, 1.1 (released date is end of April).
As far as how to create tables (this is included in the 1.1 doc), you create a table header by using ||, and cells with a single |. Like this:
||header1||header2|| |cell1|cell2| |cell| cell |
As a cheat I often switch back and forth between the plain text editor and the GUI editor. For example if I have a very large table, it's easier to edit the contents in the GUI editor where you can see all the cells, and what row you are in without the markup. This also can help you determine what the proper markup is--create the desired functionality in the GUI editor, and then view the wiki markup in the plain text editor.
Sometimes the round trip hammers the document. It seems that the RTE sucks up a lot of whitespace and/or newlines, causing paragraph text to get sucked into header lines, etc.
Do you plan to support internal links (or sections with automatic TOC) in the next version ? This is quite useful for longer wiki documents. Something like the === syntax in MediaWiki.