The Beta version of the Enemy Territory: QUAKE Wars Software Development Kit has just been released! The SDK contains all of the tools used to develop ETQW along with a few extra bits - check this dev blog entry for a complete breakdown of the contents. Please note that this is an unsupported release, so Activision Customer Support will not be able to assist you with technical issues arising from using the SDK. With that out of the way, you can grab the SDK Beta from the mirrors below:

Enemy Territory: QUAKE Wars Software Development Kit (Beta)
• Fileshack
• Internode
• K-Files.de
• Worthplaying
• EGN Australia
• own3d.at
• PlanetQuakeWars.net
• QuakeWars.co.nz (New Zealand only)
• Wolfenstein-City.de
• Official .torrent

Once you’ve got it installed and have started tinkering with it, don’t forget to stop by the ETQW Mods and Editing Forum to share your creations with the rest of the community. We’ve also got our official ETQW Editing Wiki on the way; it’s currently set to launch later in the week.