Here is information about upcoming and past releases. Each release goes through a stabilization phase as described in the Hacker's Guide to Subversion. The CHANGES file contains an overview of what's new in each release. Releases are always source tarballs; binary package updates for various OS's generally follow the source tarball by a few days.
For information about what features are being worked on, and how we coordinate features with releases, please see the roadmap page.
Subversion 1.6.0 (future):
Feature and bugfix release.
See open issues marked for 1.6 or 1.6-consider.
Subversion 2.0.0 (future):
Feature and compatibility-affecting release.
See open issues under consideration for 2.0
(absolutely not commitments, and likely to change).
Information about older releases is located on a separate page.