Capt Arjun pointed this one out to the guys on the Napnuts forum, and it is truly blogworthy. (picture from Hobby Link Japan: click on the post title to go to the article in question)
According to the site, with the Tamiya Weathering Master Set B:
"... a few light strokes on the raised edges, suspension, etc. of your model with the enclosed brush and you'll have a superbly realistic effect just as good as traditional dry-brushing, but with a lot less work..."
What gets me though is the look of the packaging, which is in the same visual genre as "ladies make-up compact", down to the brush. Either this is a case of economies of scale (Tamiya leveraging the existing stock of cases and brushes already produced by suppliers, to avoid having to custom make a case) or Tamiya senses that its customers are really, really secure people.
Even the range of colours resembles those that I've seen on my wife's make-up kits. The irony of it is that my wife recently threw out a bunch of make-up powder compacts which had got too old: I salvaged the containers (which look like the one pictured here) because I thought they looked as if they could hold something useful - but now it seems that I should have saved the whole thing! My tanks could use a bit of a makeover ... and Estee Lauder has just that right shade of rust ...