I've just released version 1.5 of YARPP... the big new feature is "auto display"... if you install YARPP for the first time now, you will get a nice "Recent Posts" display in all your single entry (permalink) pages without any theme tweaking. This should be very helpful for many users.
If you don't want to use the default display, turn off "auto display" in the options (now moved to Options, where it should be) and drop
related_posts() or similar code into your theme. If you are upgrading from a previous version, YARPP should autodetect this and start with "auto display" off. If you have problems after switching to YARPP 1.5 (like all your settings being gone), I recommend deactivating and reactivating the plugin.
For those of you who are interested, tags and categories are going into the relatedness algorithm in the upcoming update, 2.0. Stay tuned.
Thank you all for your comments and suggestions. I'm hoping to make this a strong, easy to use yet versatile plugin for everyone, helping cross-linking, SEO, and—of course—readers.