The latest update to Xcode 5.1 was released recently, by Apple, and it brings fixes for reported bugs and overall improvements in stability to software development, testing tool and debugging. One week after Apple released the final beta seed to developers, the Mac App Store has Xcode version 5.1.1 available for public use.

According to the release notes,

Includes SDKs for OS X 10.9 Mavericks, OS X 10.8 Mountain Lion, and iOS 7.1.

Fixes an issue that would reposition the Interface Builder canvas unexpectedly.
Improves the reliability of Quick Look within the debugger.
Fixes an issue where test cases would report as failed when in fact they had passed.
Fixes a rare code generation issue in the LLVM compiler.
Includes additional bug fixes and stability improvements.

New improvements come with already existing features that were released in Xcode 5.1 including Instruments, Xcode IDE, iOS Simulator, LLVM compiler, and the latest OS X and iOS SDKs.

Xcode version 5.1.1 is a free download from the Mac App Store and is 2.18GB.

Source: iTunes