3.2 beta 3 is out!
http://downloads.wordpress.org/plugin/yet-another-related-posts-plugin.3.2b3.zip
I've backtracked slightly from my attempts in beta 1 and beta 2 to completely swap out the custom table-based caching with postmeta-caching. Instead, I've abstracted that cache layer and made it so that you can switch between the two. By default, it will use the custom tables (like in 3.1.x) but you can add the following to your wp-config.php file and it will use postmeta instead:
define('YARPP_CACHE_TYPE','postmeta');
I'd *love* to get feedback from those willing to try the postmeta cache, in particular in comparison to the custom table approach. Is it faster? Slower? Somehow better or worse for your platform?
In addition, a number of caching performance issues (one kind of major) have been resolved, resulting in much better cache retention!