It's an updated version of 5.0.1. It will be available to those who are not already on 5.0.1. If you are already on 5.0.1, you'd have to delete the current .ipsw from your computer, download the new 5.0.1 and then restore. This is the first time that Apple has done this. I'm not sure why they didn't call it 5.0.2 and make it available to everyone. It must not be very different from the original 5.0.1.