Xbox 360 spring dashboard update leaked?

Ruh roh, according to MyGamerCard, GameSpot supposedly accidentally posted a video of Xbox 360's spring Dashboard update. No way of knowing if it's legit (it certainly doesn't look a fake), but according to the video:

• The update hits May 7th
• Your contact list will now integrate Windows Live Messenger, and show joinable session status
• Messenger contacts can see what game you're playing, and your gamertag
• Marketplace will now have its own blade, which will be skinned independent of your theme
• Users will now get inline achievement updates
• Low-power download mode and auto-shutdown
• You can watch partially downloaded movies
• You can text chat messenger six friends playing games watching movies
• Multiple tweaks on the user interface

YouTube video after the break. What say ye?

[Thanks, Sherveen]