I\'m using Xcode 4.3.2 and it tried to install an update to the command line tools.
I clicked the update button and Xcode told me that [my apple id] does not have access
Dominik Porada details the solution at Xcode 4.5 and iOS 5.1 Simulator, ie. download the old XCode 4.4.1 from Apple and pull out the simulation. Personally, I just copied the simulator from one of my other Macs that I hadn't upgraded XCode on yet.
Not sure if it's still relevant but xcode-select --install
might do it.
I had the same problem last night after the update to Mountain Lion and Xcode 4.4.
This morning I tried to build something in xcode and it told me that developer mode wasn't enabled on the mac. Once I enabled it, I tried to download the command tools again and that happened to work fine now.
Yes its all over the Twitter... Just go to Apple Downloads and manually install it. They are investigating the issue as far as I know