This is an offshoot of this thread, which seems to have been noted as "resolved" prematurely.
Recently updated to WP 2.8.4, with no problems at all.
Was particularly happy to have nested/threaded comment replies as native to the WP experience.
Realized that my theme, Cutline 3-column right, was too old to support this, so I upgraded to the latest version, 1.4, which, per the documentation, also supports threaded comments.
I have followed the steps outlined at the WP Support thread linked to above, via the dashboard, and nothing happens. I presume there is some comments.php editing to be done, but I'm a total newb with that, and welcome VERY SPECIFIC INSTRUCTIONS, if anyone can parse what I'm talking about here.
Please let me know if I need to supply more info. Many thanks! Btw, the site in question is here.