You need to click Log Navigator icon (far right in left sidebar). Then choose your Debug/Run session in left sidebar, and you will have console in editor area.
The console is no extra window anymore but it is under the texteditor area. You can set the preferences to always show this area. Go to "General" "Run Start" and activate "Show Debugger". Under "Run completes" the Debugger is set to hide again. You should deactivate that option. Now the console will remain visible.
EDIT
In the latest GM Release you can show and hide the console via a button in the toolbar. Very easy.
In XCode4 double-click your Project (Blueprint Icon).
Select the Target (Gray Icon)
Select the Build Phases (Top Center)
Add Build Phase "Run Script" (Green Plus Button, bottom right)
In the textbox below the Shell textfield replace
"Type a script or drag a script file from your workspace" with
"open ${TARGET_BUILD_DIR}/${TARGET_NAME}"
This will open a terminal window with your command-line app running in it.
This is not a great solution because XCode 4 still runs and debugs the app independently of what you're doing in the terminal window that pops up.
You can always see the console in a different window by opening the Organiser, clicking on the Devices tab, choosing your device and selecting it's console.
If you just want to have the log output display when you run your app then you can go into XCode4 preferences -> Alerts and click on 'Run starts' on the left hand column.
Then select 'Show Debugger' and when you run the app the NSLog output will be displayed below the editor pane.
This way you don't have to select on the 'up arrow' button at the bottom bar.
In Xcode 4 short cut to display and hide console is (command-shift-Y) , this will show the console and debugger below ur text edior in the same window.