I just bumped the stable version of the HIG to v2.2.
Really it’s more of a 2.0.1 release, as none of the content has changed apart from the illustrations, which have all been updated to use the Clearlooks theme. But given the number of people involved (Mihai Anca, Denis Anisimov, and Wouter Bron did the bulk of the illustrations) and the length of time it’s taken me to integrate them (about 9 months!), 2.2 seemed more appropriate…
(Unfortunately, nowadays you don’t get to see new versions of the HIG online until there’s a new release of gnome-devel-docs, and I know I just missed 2.24.0. But hopefully there’ll be another one along soon.)
Of course, this doesn’t address the more fundamental issue that the HIG now lags several years behind the curve of GNOME development. I’d like to think we’ll get around to doing something about that before the year is out.