I've partially rewritten the StableVersion extension. It now can
* store multiple stable versions (someone wanted this; I can turn that off)
* store multiple types (not actually supported yet, but the potential is
included), e.g.:
** stable
** stable candidate (someone wanted this)
** "soft-protected"
** other "levels of stability" like "thoroughly reviewed"
And most important:
When you click on the "declare this stable" link, it now caches the
source *with replaced templates*, meaning the stable page will look the
same even if the templates it uses were changed or deleted.
With some help *ahem* the feature could go live this year, IMHO.
Magnus