Keyword expansion with tags?

[Kurt Granroth]

Is it possible to expand tags with the 'keyword' extension?  I'm 
specifically thinking of emulating the behavior of the CVS $Name$ keyword.

To start, I realize that keywords aren't encouraged in Mercurial and 
don't make anywhere near as much sense in a DVCS as they do in something 
like CVS.  HOWEVER, they are necessary for our build procedure for 
several reasons:

1. Quite a few of the $Name$ instances are in non-compilable files so 
the simple -D Makefile trick won't work
2. There are a *lot* of instances of $Name$
3. It's possible to have multiple tags on the same patch and so we can't 
commit the tag name into the changelog directly

Yes, I could put some sed script in the makefiles (SConscripts, 
actually) that dynamically changed the keywords during the build... but 
I'd prefer to do this via hg, if I can.

So is it possible?

Kurt