Just about a year ago, most Google help forums moved from the old Google Groups platform to a new platform. But not all have moved. The Google Reader group finally moved to the new platform a day or two ago.
I asked in a Google Reader Help thread, "what took so long?" The response from Roger from Google was "We liked our old group so much we had a hard time letting go! :)" Cute.
But there are other Google support groups still on the legacy system, including the AdWords API Group. I am not sure what the hold up is, but I don't know why they are staying in the old platform.
I assume most Google groups within Google have already moved, based on what I am tracking.
Google Reader, welcome to the new forum.
Forum discussion at Google Reader Help.