While most WSN files fall under a proprietary license described in license.txt, there are exceptions which are offered under more open licenses. In some cases this is to facilitate distribution of changes, in the case of LGPL files it's a legal requirement to maintain their license, and in some cases borrowed/modified public domain or BSDish-licensed code is being passed on as a gesture of appreciation for the work others have put into it.

These files should be considered public domain, you can do whatever you want with their code:
- /templates/ (all files beneth the directory)
- /integration/ (all files in the directory)
- /databases/ (all files in the directory)
- /languages/setup/ (all files in the directory)
- classes/pagerank.php
- classes/openid.php
- classes/smtp.php
- paypal.php
- 2checkout.php
- nochex.php
- ulsearch.php
- servertest.php
- languageextras.php

The /jquery/ directory falls under the MIT license.

These files fall under the Apache 2.0 License:
- googlecheckout.php

These files fall under the GNU LGPL (which you can find a copy of in fckeditor/legal.txt):
- /fckeditor/ (all files beneth the directory)
- classes/activecalendar.php 
- includes/blogping.php
- videoplayer.swf (download the source at http://scripts.webmastersite.net/wsnlinks/videoplayer.tar.bz2)

These files have permissive, BSD/MIT-like licenses specified inside them:
- includes/xmlrpc.php

These files have custom licenses specified within them:
- includes/padfunctions.php (PAD SDK license)
- fixiepng.htc (http://creativecommons.org/licenses/by-sa/2.5/)