I've been holding off on commenting about the XNA Game Studio Express announcement because I didn't want to sound like a wet towel, but enough is enough :-)
Let me preface this with the fact that This Is A Good ThingTM, but lets take it for what it is.
Microsoft have enabled anyone to write code for the Xbox 360, and deploy it locally to your own console. Yes you can share the fruits of your efforts with others who have also subscribed to the service, and only in source form. I'm sure this will change in the future, but AFAIK, you can't share the compiled final product with your mate who isn't a developer.
Ok, so with that out of the way, here's the other thing.
It isn't going to come with Will Wright in the box. That's right folks, pesky things like game design, art creation, and coding mojo are still issues.
There won't be a “Make Triple-A Title” button.
I'm sure that XNA Studio will provide a ton of graphics clip art, sample models, and sample code, but there aren't going to be sample game designs, sample cool new ideas or sample innovative game mechanics.
Oh, and one more thing. Anyone can make a game with their PC right now. Just download Visual Studio Express - it's free, or maybe pick up a copy of Torque Game Builder from Garage Games - it's only $100.
What Microsoft have done is provided a cheap way for hobbyist (or cash strapped indie) game developer to target the Xbox 360. This is a good thing - it was very expensive beforehand. I'm sure that a few of these titles will be picked up by mainstream publishers, or Microsoft itself.
Just don't expect thousands of high-class titles to start rolling out of basements anytime soon. It's just another platform. Albeit a cool one.
Now, where do I sign up? :-)