Details of the "Tsunami" update include (as posted on the Xbox.com forums):
What It Is: Developer support for integrating team/clan functionality into their titles.
What It Means to You: It’s all tightly integrated into the service with built-in support for messaging, stats, competitions, storage, and presence.
Just Imagine: A kind of automated clan communication set up that notifies the entire team of matches, strategy, and even competitions.
What It Is: Easily build different types of competitions into titles that
can be created and administered by the publisher and/or users.
What It Means to You: It’s all tightly integrated with the rest of
the service and makes playing in and creating competitions a total breeze.
Just Imagine: Creating your own tournament and having Xbox Live do all of the work for you…you just create, invite, and play.
MSN® ALERTS AND MESSENGER INTEGRATION
What It Is: Invitation and Presence-based alerts and a new Xbox/MSN Messenger tab with user contextual information.
What It Means to You: Allows existing Xbox Live users to engage more with their Xbox Live community by extending the Xbox Live messaging and presence systems beyond the console.
Just Imagine: You’re at work when you get an alert that one of your buddies has just logged onto Xbox Live and has sent an invite to your PC to take him on in a game. Talk about inspiration for getting home early!
TITLE MANAGED ONLINE STORAGE
What It Is: Provides user profile data storage along with a simple way for titles to dynamically manage game influencing data on the fly.
What It Means to You: Create and share mottos, emblems, and custom content along with titles; create and update maps, rosters, and other environment data.
Just Imagine: Creating a custom logo for your squad and playing on maps that you’ve just created!