WordPress 2.0.7 has been realease to address a few security issue that showed up in 2.0.6. Everyone running 2.0.6 or lower are adviced to get this upgrade ASAP.
Change Log
wp_unregister_GLOBALS() to work around the zend_hash_del_key_or_index bug in PHP 4 versions less than 4.4.3 and PHP 5 versions less than 5.1.4 with register_globals set to “On.â€304 Not Modified headers instead of mismatched 200/304 headers (a.k.a. the FeedBurner bug).304 Not Modified fix from WordPress 2.1