Like the update for unlocked devices, this one includes:
Froyo 2.2.2 with the next generation of Dell Stage User Interface with added widgets for Movies, eBooks, & Streaming Music. This software also includes pre-loaded apps such as: Car Dock Mode; Enhanced Email, Gallery, Browser & Phone apps; Napster, Accuweather, CoPilot Live, Evernote & Zinio Reader apps.
If your AT&T-locked Streak hasn't received the update notification yet, you can either wait patiently for it arrive or keep tapping Menu > Settings > About phone > System updates.
How's it going so far?
Thanks, sakanagai!