The administrative control panel now allows admins to opt in to some new application features before they're generally available to Google Apps domains. This provides access to new, possibly less stable application enhancements.

Editions impacted:
Standard, Premier, Education and Partner Editions

Languages impacted:
US English

How to access what's new:
From the US English, next-generation administrative control panel, click 'Domain settings' and check the box next to 'Turn on new application features to my domain before they are rolled out to all Google Apps customers.'

For more information:
http://www.google.com/support/a/bin/answer.py?answer=82691