I don't know if this is intended, but with the default theme, ordered lists have no numbering (see http://support.djangobb.org/topic/79/?page=1#post-307 with the default theme).
To correct this (was this the correct place ?), I've added this code in base.css (because I don't want to cancel the numbering in any style, but I guess putting it in default.css would be better) :
.postmsg LI
{
LIST-STYLE: decimal inside;
}