Here are the steps to get you up and running in less than 5 minutes:

1. Install Java SE 1.5+
2. Go to OW2 Forge download page. Select the last eXo file for tomcat in the "eXo All-In-One" section. It should look like: exo-eXoAllInOneProduct-x.x-tomcat.zip where XXXXXX is depending on the version you want to download. .
3. Unzip that package under a path that does not contain any space (in windows).
4. Go to the bin/ directory that will be extracted. There, run the command :
windows: eXo.bat run
linux and Mac OS: ./eXo.sh run
5. Login as the administrator using the username "root" and the password "exo".
6. Enjoy the eXo style and knowledge !