As long as your source code is kept in a single tree, Subversion's $Revision$ works perfectly well. The only thing you need to do differently than in CVS is that revision numbers are integers. So you get something like this (untested) code:

# Subversion example
($VERSION) = (q$Revision: 123 $ =~ /(\d+)/);
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For the record, that is what I do at $work.

As noted in the link you were dealing with, if you're using a distributed source control system, then you run into problems with different people having different versions. The cheap solution to that is to define one version as canonical, and have that version use revision control to produce version numbers. So you can have a script which runs on that system that, after you take patches, uses its revision number to set the appropriate $VERSION and then produces a patch for everyone else. As long as only one machine generates $VERSION patches, you shouldn't have too many annoying conflicts to resolve.