The New Xbox Experience (NXE) launches today. This is a real big milestone for the Xbox 360 as it reinvented itself in several directions with this software update.
Besides avatars and a neat new user interface, the Netflix movie streaming is the hottest new feature of the NXE update. Xbox 360 users can instantly stream movies from their Netflix subscription on the Xbox 360. At launch there are also 300 HD choices available. The HD content including "La Vie en Rose," "Flawless" and "Heroes" is still streaming with standard audio, but possibly multi-channel audio will be added soon. Sony Pictures Entertainment is apparently messing with the Netflix movie streaming on the Xbox 360 by not having granted licenses for their movies on the Xbox 360 yet. Update: Sony says that the licensing issues have nothing todo with the Xbox 360, still a resolution is not here yet. Via MTV.

Apparently a few hundred titles on Netflix are not streamable right now on the Xbox 360 says Netflix. This limitation causes you to miss out on watching movies like Superbad and We Own The Night. There is no word yet from Netflix on when Sony will grant the license for their content to be streamed onto the Xbox 360.

This is of course not a sustainable situation for users. There is no sense for Sony to block their content in the long run. This will not help PS3 sales, just because Sony movies do not stream on the Xbox 360 now.
More details on this interesting little war on MTV.
See also the Microsoft NXE page for an overview of all the new features you are getting today.