Last month I read a great thread on IAI-members mailing list, started by Jennifer Hale and titled "Mobile sites: Worth the time?".
The right question is: how much is it profitable?

Here's some data:
Mobile is the seventh of mass media and the internet adoption (feature and smartphone) is 12%.
32% of mobile subscribers used browser in May 2010 (Comscore).
In 2011 smartphones will lead US mobile phone market (Nielsen).

So that's why it's so important for a web oriented Corporation to design for mobile.
Now let's take a look on what Google calls a "new experience" !?

First of all, in a Google video, we see an iPhone as the main character. Weird 🙂
As we know, the iphone aspect ratio is 3:2 (480×320 for 3G/3GS and 960×640 for 4G). So the design has essentially two sections: the player (horizontal orientation) and the website (vertical orientation).
The youtube experience is obviously reduced in main actions. For example in the detail bar you've 5 calls to action: iLike, iDontLike, Save, Share, HQ. There's a Hub&spoke button on the top bar that takes the user to the main menu: Home, Browse, Favourites, Playlist, Subscriptions, Uploads, Sign out, Settings (very heterogeneous and one item less than nine :).
The comment and social section are below the player. It means that the design is based on "watch content" scenarios.
I like it, but I don't think it is a new experience at all 🙂
 

More findings in The Mobile Question: Lessons in Design and Strategy for Your Mobile Experience by Jeremy Johnson (you can listen the speech @IA Summit 2010 reported by BoxesAndArrows)