I updated wordpress and then updated to RS 1.3.59 and noticed some serious issues.
One interesting bug involved wp_list_pages (set to echo out the results, not the default) was outputting all pages without any hierarchy, i.e. just a flat list of all pages.
I also noticed that custom queries that used WP_Query and the taxonomy feature tax_query were not functioning at all. Oddly they would work if instead of looking for a particular category (i.e. a tax_query with a parameter of 'id' => 53), I told it to NOT look for all other categories (i.e. a tax_query with 'id' => array(51,52) and the NOT IN comparator.
I'll keep an eye on the development log to see if anyone else is having issues with the 1.3.59 update but turning the plugin off definitely corrected these issues and they are not present when using 1.3.57.