Brian’s threaded comments is one of the most used plugins amongst wordpress bloggers. I’m a big fan of it myself however as I have mentioned a few times in the past, it’s very buggy and clashes with a lot of designs. Thankfully, Alex Sysoef has been busting his ass fixing the plugin and has released a fix.
I’ve not had a chance to test the upgrade personally as yet however from the comments left already it looks like he’s done a good job. If you run a wordpress blog and are interested in using threaded comments on your plug then I recommend you check it out. 
I prefer threaded comments myself, just never had a plugin that would do it for me. I will download the plugin and see if I can get it up and running without any problems.
Always appreciate a good plugin. Thanks