Comment text not escaped properly

That is because the comments have HTML formatting allowed. you can use &lt; and &gt; for < and > respectively.

That doesn't solve the issue. There are only a couple of tags allowed / understood. Simply cutting everything else inside <>, means that when I paste in a piece of code or a command or even simple text that includes those characters:
- text will be removed - many words may be lost
- the comment cannot be fixed later on
- comment may become incorrect but may still look ok - and the situation will just confuse readers

Why not just interpret tags that can be interpreted, but escape everything else? If someone writes:
  <bn>some text</b>
by accident, people will understand what was supposed to happen when they see the original text. On the other hand, if someone writes:
  some_command < some_file > other_file
and people see:
  some_command other_file
information will be simply incorrect (which might lead to data loss in some extreme cases).

Allowing users to edit the comment could also help - assuming that author notices the mistake (why would I read the comment I just submited though?)
I know how to escape the contents properly, I know that brainstorm uses markup, yet I made that mistake 3 times already.

Commented on the "incomplete" status 3 weeks ago. Reverting to new.

Yet another problem with not escaping user's text -> if you write an "arrow" to mark some text like this:

- some
- list <--
- blah

then everything after "list" will be removed from the post (like an unclosed tag)

Yet another comment - braces seem to be disappearing from comments - probably for some reason similar to lt/gt signs problems.

To see that is can cause problems when people talk about code, look at http://brainstorm.ubuntu.com/idea/19903/ and comments from "bryonak" and "gelsbern".