As previously mentioned on this site the Xbox 360 system update that will provide USB memory storage on your consoles is heading your way tomorrow (6 April).
I just snagged this little update from the Xbox Live Operations Blog:
Starting at 0200 Pacific on April 6th we’ll be rolling a system update out on Xbox LIVE – to see what time that is for you, click here. It may take a few hours for everyone to be prompted for the update.
Let us know when you get it and what you think. I am ready to plug in a couple of USB flash memory devices and check it out myself.