Well at least this all prompted me to look at linuxfr.org, previously the most prominent site to use Templeet, and read discussions on the fact that it switched to Ruby on Rails a couple of years ago...
Basically, the thinking was also that static sites are no longer that important, and that anyway, the site was too dynamic to allow for proper use of Templeet's best feature. I think they went with the second best caching method (and first for dynamic sites...), i.e. they're caching only parts of a page, and then serving these static blocks dynamically.
I don't think Wedge or SMF would go to these lengths, mostly because there are so many potentially pages in a forum, if you create a static cache of all those things you'll end up with a huge cache folder... I guess, the best that can be done is to do a temp cache (i.e. expiry date like in cache_put_data), ensuring that only the currently most visited pages will be statically cached, or at least partially.
That's the direction SMF was going, I think... At some point.