I have the same problem too, since I upgraded from beta1 to beta2.
When editing a comment it just posts a new comment and the old one is left intact.
And the separators for reply, quote, edit etc. are gone.
I use the following template settings:
HTML: SSlide-emotop
CSS: css-blackg
Copy current standard template to customized template directory: No
PHP-version: 5.2.9-2
MySQL version: 5.1.33
Joomla version: 1.5.11
Running on WAMP server 2.0
EDIT: I uninstalled beta2 and downgraded to beta1. But the bug still remains. The separators are back though.
EDIT 2: I think I forgot to remove the module-part. Anyway, I did a FULL UNINSTALL and after that it worked again without bugs in Beta1.