Yes. It's a modification of markdown. Some syntax is the same, but there are a few differences.
Text surrounded by asterisks (*) is italicized.
Text surrounded by plus signs (+) is bolded.
Text surrounded by vertical bars (|) is quoted. If you double-click a paragraph, it will be quoted.
Text surrounded by tildes (~) is blocked out.
Symbols such as *, +, |, and ~ can be used literally by placed a \ in front of the text.
A user's name surrounded by at signs (@) links to their profile, and the user is notified that you mentioned them.
A word surrounded by hash signs (#) becomes a tag and links to posts with that tag.
Blank lines separate paragraphs.
Text after a blank line that is indented by two or more spaces is reproduced verbatim in a different font.
URLs become links.
Text can link to URLs by using the following format: /linked text
That was not easy to do.
Image URLs (.png, .tif, and .jpg) will embed automatically.