I would like to start tagging my deployed binaries with the latest SVN revision number.
However, because SVN is file-based and not directory/project-based, I need to
"svn info" will show you the working copy's revision number (see the "Revision" line in the output from "svn info"). Your build system probably allows you to place the relevant part of "svn info"'s output somewhere where it will be reflected in your application. For example, you may specify that when building, a temporary (un-versioned) file should be created, containing output from "svn info"; and you then include this file when compiling.