I'm sorry I haven't checked the plugin code but I just noticed strange multiple entries from YARRP in my wp_options table. When I run
SELECT option_name, option_value FROM wp_options WHERE option_name IN ('yarpp_rss_use_template', 'yarpp_use_template')
I get seven entries each (14) with blank option_values. They're blanks, not nulls.
I just thought of giving you mitcho a heads up in case you might know what these are.
http://wordpress.org/extend/plugins/yet-another-related-posts-plugin/