The next time you sign into Xbox Live you will receive a prompt for a mandatory update. This update is not the one you have been waiting for that includes Twitter and Facebook, that one is still scheduled for next month unless you got into the preview program, but instead this is an update that will provide support for Xbox 360 Wireless Network Adapter.
Just seems like we should have had WPA2 support awhile ago, but I guess it’s better late than never. Also this update will not affect your preview program update that you may have received. Concerns where raised about the the wireless update overriding the preview, but there is no need for concern.