Writing on his blog, Microsoft's Larry "Major Nelson" Hryb has told Xbox 360 users that, while the New Xbox Experience is now out and out there, it's not out there for everyone. Looks like instead of flipping a single, enormous, magic switch, Microsoft are having to flip a whole ton of switches, one after the other
The New Xbox Experience is in the process of being deployed to all Xbox LIVE members, but it will take a few hours for everyone to get the prompt to update to NXE….be patient!
Now's a good time to tell you once you do get the prompt...be patient again! Your screen may go black and/or look like it's frozen up. Don't panic. That's just the NXE building up the confidence to do it's stuff. Top 10 things to do when you get the New Xbox Experience [Microsoft]