Did a search and couldn't see anything about this. Just so everyone on live doesn't think its a problem on their side..
For 24 hours starting 9am [10am CET] on September 29th youll notice that your Xbox LIVE service is temporarily unavailable. This is, in fact, terrific news!
This particular Xbox LIVE downtime is especially important because it will ready the Xbox LIVE network for the arrival of the New Xbox Experience later this year an amazing free update that will change the way you enjoy Xbox 360 entertainment forever. Think of it as the first tremor before the earthshattering arrival of something extraordinary!
Very soon the New Xbox Experience will transform your Xbox 360 into a limitless world of home entertainment in which the best games, movies and TV shows live side by side with your personal pictures and music library. Everything you enjoy about your Xbox 360 can be shared at any time with friends via Xbox LIVE using cool customisable animated Avatars.
So remember, Xbox LIVE will be unavailable from 9am [10am CET] on September 29th for 24 hours. You wont see the New Xbox Experience when LIVE comes back online, but you will be all ready to receive it when it launches later this year.
Its proof that good things come to those who wait!