ofxKinect is an Open Frameworks addon for the Xbox Kinect that runs on Linux and OS X.
OpenFrameworks is a cross platform open source toolkit for creative coding in C++.
http://www.openframeworks.cc/

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To use ofxKinect, first you need to download and install Open Frameworks. ofxKinect is developed against the latest version of Open Frameworks on github, but will also work with recent releases of OF like r62.

If you would like to work with the latest code, you should place the repository in a subdirectory of your apps/. For example, OpenFrameworks/apps/examples/ofxKinect

To get a copy of the repository you can download the source from http://github.com/ofTheo/ofxKinect/zipball/master or, alternatively, you can use git clone.

If you're using OS X, open the XCode project and hit "Build and Run". You might want to chose "Release" instead of "Debug".

If you're using Linux, you should open the Code::Blocks .cbp and hit F9 to build and run.
You should create some udev rules in order to run the app without root privileges:
As root write this to /etc/udev/rules.d/51-kinect.rules (this works on Ubuntu 10.10):
SUBSYSTEM=="usb", SYSFS{idVendor}=="045e", SYSFS{idProduct}=="02ae", MODE="0660", GROUP="plugdev"
SUBSYSTEM=="usb", SYSFS{idVendor}=="045e", SYSFS{idProduct}=="02ad", MODE="0660", GROUP="plugdev"
SUBSYSTEM=="usb", SYSFS{idVendor}=="045e", SYSFS{idProduct}=="02b0", MODE="0660", GROUP="plugdev"

To develop your own project based on ofxKinect, you will need to make a copy of the repository, at the same directory depth, and modify the example application. If you are comfortable setting up a new project and importing the libraries into it, you might also consider moving ofxKinect/src/ofxKinect into your addons folder so you can simply update that one folder to bring multiple projects up to date.