Simple tags are allowed: b, u, i, strike, big, small, p, br, table, thead, tfoot, tbody, tr, td, ol, ul, li, blockquote, br, center, cite, code, dl, dt, dd, em, h1, h2, h3, h4, h5, h6, del, ins, em, strong, dfn, code, samp, kbd, pre, var, cite, blockquote, hr. They can't have attributes, because I'm too lazy to write something that allows that. Two newlines are replaced with line breaks.
The system attempts to prevent useless posts.
The comments are stored using shelve. You can open a comments database in python by using shelve.open.