Since Spring Security is an Open Source project, we'd strongly encourage you to check out the source code using subversion. This will give you full access to all the sample applications and you can build the most up to date version of the project easily. Having the source for a project is also a huge help in debugging. Exception stack traces are no longer obscure black-box issues but you can get straight to the line that's causing the problem and work out what's happening. The source is the ultimate documentation for a project and often the simplest place to find out how something actually works.
To obtain the source for the project trunk, use the following subversion command:
svn checkout http://acegisecurity.svn.sourceforge.net/svnroot/acegisecurity/spring-security/trunk/
You can checkout specific versions from http://acegisecurity.svn.sourceforge.net/svnroot/acegisecurity/spring-security/tags/
.