WordPress SEO looks like it could be an excellent WP plug-in but, unfortunately, I'm having a problem with sitemaps. When I click to "(Re)build XML sitemap", I get a fatal error:
Fatal error: Call to undefined function: memory_get_usage() in /path/to/wordpress/wp-content/plugins/wordpress-seo/admin/ajax.php on line 59
I tried disabling all other plug-ins in case there was a conflict but no go. I'm running the latest WP (3.1) on a linux server with PHP 4.4.9.