I suggest you checking your webmaster tools account frequently, this is a step by step tutorial how to fix 404 not found webmaster tools error by adding 301 redirect htaccess, permanent redirect in wordpress blog.
If you ever encounter 404 page error, wordpress not found, read this experience.
Wordpress custom permalink not working? Changing your permalinks should be done after wordpress installation. Why? Because in my experience, it was terrible to wait for search egines re-indexing your new permalinks. Especially if it happens to newbie like me.