I had no idea of what XM Radio. And I'm still not sure of what XM Radio is after looking at the website they recently launched. Don't get me wrong, the site is very nicely designed, the animations are lovely, and the interactivity is fun, but I find it a bit hard to understand the connection between the animals and the satellite radio.
I realize I will sound picky (but this is why you like me, right? ;-) but, in my opinion, the site lacks in concept, not in execution. Of course there are links around the site that allow you to discover the XM world, but they aren't really in the context of the storytelling.
This said, I still think The XM Wild Ride is a very nice experience, amusing and interactive. The "Help the Hippo" advergame is fun and actually more difficult than you might think.
The agency is firstborn multimedia.