Well dismiss me if I’m a little too late for this but just now I encountered this client who needs to update a wordpress theme, the comments section or comments.php to be precise, to accommodate some of the new features introduced in WordPress 2.7, comments threading and comments paging.
The easy way — for new themes
Just go download a distribution of wordpress 2.7, and unzip the package (install it, probably), click your way into wp-content/themes/default (the Default theme) and open comments.php with your favorite dev editor.
There’s the code you need to implement comments threading and comments paging in wordpress 2.7 in case you need to create new themes dedicated for version 2.7. Also, you have to explicitly enable threaded comments in wordpress administration panel: Settings –> Discussion –> Other comment settings –> Enable threaded (nested) comments. It’s disabled by default.
Update old themes to accommodate the threading feature
For old wordpress themes, if yours or your client’s blog has already updated to wordpress 2.7 (has to, because this change may make your theme backward-incompatible), to integrate the comments threading and paging, you need to follow these steps by Will to edit 2 files in your theme, header.php and comments.php.
This tiny tutorial is written and human friendly, you won’t be bitten. 😉