Today i replaced bbmarkup by postmarkup [code.google.com] back.
I hope that now postmark is more secure as 1 years ago )

Some examples from postmarkup doc:
[b]Bold[/b]
Bold
[i]Italic[/i]
Italic
[u]Underline[/u]
Underline
[s]Strikethrough[/s]
Strikethrough

[list=a]
[*]Alphabetical item 1
[*]Alphabetical item 2
[/list]
  1. Alphabetical item 1
  2. Alphabetical item 2

[code=python]
def main():
    print "This is some Python code"
[/code]
def main():
    print "This is some Python code"

[google]DjangoBB[/google]
djangobb [google.com]