Matt has an interesting blog post at the WordPress blog about why you should keep your WordPress version up-to-date (as if you needed another reason). Matt compares 3 types of WordPress security advice: snake oil. Club solutions and real advice (see his post for what he means by Club solutions). The only thing I would add to Matt’s post is that you should also make sure you keep your plugins up-to-date as well — as they can be another security hole that can potentially be exploited. Check out Matt’s post for more info on why you should always be on the latest WordPress version.