I left it out for 1.3.2 to think a bit more on the user interface. The best solution I have in mind so far is to integrate it in the "Prepare offline usage" dialog in the Routing activity (so you can either download along the route or the currently visible region). The drawback is that people might expect it elsewhere as well (I'd expect to download tiles along the route only in the routing activity, but downloading tiles for the visible region would suit in other activities as well).