Assuming that each release is tagged, you can run SVN Info/path/to/svn/tag and return the following information:
[Plain] View plain copy Path: [Path] URL: [URL] Revision: [Current Revision] Node kind:directory last Changed Auth Or: [author] last Changed Rev: [Specify the revision number of the final path change] <-This is the message we want. Last Changed date:yyyy-mm-dd Hh:mm:ss
For example, suppose you want to get the revision number of Release 2.0 of Apache Commons Math
[Plain] View plain copy svn info https://svn.apache.org/repos/asf/commons/proper/math/tags/MATH_2_0 path:math_2_0 Url:https://svn.apache.org/repos/asf/commons/proper/math/tags/math_2_0 Repository root:https://svn.apache.org/ repos/asf Repository uuid:13f79535-47bb-0310-9956-ffa450edef68 revision:1544028 Node kind:directory last change D AUTHOR:NIALLP last Changed rev:909837 Changed date:2010-02-13 23:18:38 +0800
As you can see, the corresponding revision is 909837.