Yeah!. The problem is solved in Xcode 4.5.1. You can Update from 4.5 to 4.5.1 at the Apple App Store.
See the release notes at https://developer.apple.com/library/mac/#releasenotes/DeveloperTools/RN-Xcode/_index.html#//apple_ref/doc/uid/TP40001051-SW208
--------- Here is the older work around, which of course, still works :-) ---------
[WORKAROUND] Xcode 4.5 Output Window input echo problem
See also Apple developer forum thread at: xCode 4.5 console input at https://discussions.apple.com/message/19648239
It seems that a when running a Console application in the IDE, the characters do actually go into the application but only the first character typed in during that input operation is echoed. Once the Return key is pressed, we then see the first character of the next input line.
Workaround: Create a second Window. The "All Output" section of the non-focused window will show the proper echo of the input characters.
Using File->New->Window and resizing the windows so we have the smaller window on top, we click to focus on the Output window and Run the application.
In the window on top (which has keyboard input focus) we type 67 and press the Return key , we see that the lower window shows each character as it goes in but the upper window only shows the first character.
We continue with 80 and Return, followed by 90.7 and Return and see the problem continues consistently.
The second visible Output window lets us workaround the input echo problem, but Apple really needs to fix this.
Here's the Xcode version screen: