Now that Moonlight 1.0 is out, I should talk a little bit about Aaron Bockover's amazing Moonshine plugin.
Moonshine's About Box while playing HBO.com
So when you visit a page that in the past used to embed the Windows Media Player (for example at HBO.com or at C-SPAN), instead you get a Moonlight-based rendering engine and uses Microsoft's Media Pack for doing the video and audio playback.
It is trivial to install it, just go to this page and click on the moonshine that is right for your platform.
Internally we referred to this project as "Pornilus" a homage to the Roman senator and patron of the arts from the 3rd century. And like Pornilus, we want to bring the arts to the people.
Cute fact: Pornilus/Moonshine will pick-up your Gnome theme and theme itself accordingly.
Oddly enough, there is no Wikipedia page for Pornilus yet. Someone needs to correct this.