You can usually force it by switching your system over to instant on (or power saver, power off, then instant on, then power off and wait) and turning the system off and waiting. I haven't tried it yet, but that's how I've got previous updates to go through.

Good update, though. Here's to hoping for external storage support in May's update (and that there's no limit on the external storage drive like what there is on 360). I'm starting to run low.