Subversion 1.7 introduces a complete rewrite of the control system's working copy meta-data management system, improved HTTP protocol usage, a new remote dump-file tool (svnrdump), and introduces "svn patch" as a way to apply patch files to a working repository.
There's also other enhancements such as enhancing some client command-line sub-commands (svg log printing diffs, an "svn relocate" sub-command, new "svn diff" options, etc), API changes, improved HTTP library, merge-tracking enhancements, and server-side performance tuning. The algorithms for the diff, merge, and blame commands have also undergone performance optimizations. There's also plenty of bug-fixes within the new Subversion release.
Some of these new features, however, are only available when the Subversion server is upgraded to version 1.7.
The license of Subversion has also been changed with this release to the Apache License, Version 2. Previously the code to this revision control system was made available under a modified Appache license. The copyright to the collective Subversion work is also now owned by the Apache Software Foundation.
See the release announcement for Subversion 1.7 or the release notes, which go into much more detail regarding these changes.