In a recent post, I suggested you to download WordPress 3.1.3 update because updating WordPress has a lot of benefits. You do know that WordPress blogs are known to be targets for hackers. If you keep your WordPress blog updated to the latest security patches, a hack is less likely to happen. This is the reason why Google wants to remind WordPress blog owners to update their blogs to prevent hacks, malware injections.
Remember that if your blog gets hacked, there are big chances that it will not index on Google anymore! There are some webmasters that have received notifications from Google Webmaster Tools to update their WordPress Blog. You can see an example here : Bas van den Beld received a new notification from Google Webmaster Tools that has never been seen before. Here is also a tweet from Matt Cutts notyfing people that they should update WordPress: Matt Cutts
What are you waiting for? Update your WordPress Blog
need to update.. but don’t forget to backup data… monthly or weekly…