Quote by Eurogamer:
Aaron Greenberg: The team is focused on launching the Primetime channel for the spring. New Xbox Experience allows us to provide new features on a more regular basis, so you'll see us deliver smaller updates throughout the year."
"We will definitely package some things together, but we haven't specifically committed to doing just two big updates. We want to add new features when they're ready. Then, for holiday perhaps, we'll do something big. But exactly how that will work remains to be seen.
It might also be a good idea to start saving up some money now as Greenberg also mentioned that there will be a lot of other new goodies that we don't know about yet. "I can safely say that if you're an Xbox 360 owner today, you will end 2009 with a whole slew of new features, new content, new partners, new games that today you don't know about."
Since we already know they are planning on releasing Halo 3:ODST later this year, hopefully we can expect a few other big titles to drop that we don't already know about. The complete interview can be found at http://www.eurogamer.net/articles/microsofts-aaron-greenberg-interview