Hi there, welcome to the community.
First I think you're making a few wrong assumptions, the tutorials that you saw in Flex in a Week were targetted for the Flex SDK 3, and Flex Builder 3. Flash Builder 4 Beta 1 is the new name for the next version of Flex Builder, and you'll most likely use it to create projects that target the Flex SDK 4.
You can ask yourself what the heck is the Flex SDK, you can find a great explanation in here:
And what is Flex Builder now Flash Builder?
It's the IDE for building Flex apps that target the Web using the Flex SDK or the desktop using the AIR SDK, you can also use it to develop pure AS3 projects, and more.
If you're an enthusiast, and want to test Flash Builder Beta 1 you can find several tutorials in here:
You could also find several examples in :
I think Adobe wouldn't update the Flex in a Week tutorials right now, because the Flex SDK 4 is still under development and things can change drastically as happened with the new namespaces structure.
And last but not least if you want to be up to date with the latest news about the Flex SDK 4 you can always check
I'm afraid I specifically don't want the Flex in a Week demos upgraded to Flex Builder 4. I'm using the SDK and quite honestly the last thing I want is for any tutorials to be based upon a beta version of anything. In actual fact, the tutorials should probably be based on the lowest common denominator in terms of any IDE / development kits (so probably the latest SDK) rather than include things which are only in Flex Builder (which I can't afford !).