Xcode is free from the Mac App Store or a Apple Developer Account. The optional command line tools are also available as in-app downloads or from ADC.
Apple Xcode 4.3.1
All of the disk images are identical to the ADC.
This for all the users that cannot or will not use the MAS or do not have a ADC account to download Xcode from Apple.
What's New Version 4.3.1:
* Includes SDKs for Mac OS X 10.7 Lion and iOS 5.1
* New code signing workflow supports signing OS X apps with Developer ID
* Adds installation of command-line tools to the Downloads preference pane
* Open Developer Tool menu launches Instruments, File Merge, and other tools
* ARC migration tool converts both retain/release and garbage collected code
* Additional bug fixes and stability improvements
Additional Xcode 4 content included;
Accessibility Tools - February 16-2012
Audio Tools - February 16-2012
Auxiliary Tools - February 16-2012
Command Line Tools - March 7-2012
Dashcode - March 7-2012
Graphics Tools - March 7-2012
Hardware IO Tools - February 16-2012