Hey Joe,
Thanks for pointing that out, it is a bug. I've just fixed it in my copy so it will be fixed in the next release. However you can also fix it immediately in your copy by editing
/Blog/Controls/BlogViewControl.ascx
look for this:
<fieldset id="fldEnterComments" runat="server">
and change it to this:
<fieldset id="fldEnterComments" runat="server" visible="false">
It is actually the fieldset for the legacy blog comment system rather than the new comment system.
Thanks,
Joe