The "FileHippo" site hosts a variety of "freeware" for download. (I haven't used this site, and can't speak to the safety of their downloads, but it gives a useful example.) I can, for example, download the (GPL-licensed) Handbrake program for Windows from here.
Now, while it includes a copy of the GPL in the COPYING file, etc., the installer does not contain sources for Handbrake. I can get those sources from the developer at handbrake.fr, but that's irrelevant: the FSF's interpretation of "distribution", as we've seen, includes anyone through whose hands a binary passes.
Now, if I go to FileHippo, who "distributed" the copy of Handbrake to me and demand the sources, as is my right, they can't help me: they don't have them, and they don't especially want to have them, I'd think. From their point of view, it's the developer's responsibility to make them available, if that's what the developer chooses, or is obligated, to do.
By simply having had a copy of Handbrake uploaded, and making it available to the general public, it would seem that the site is in (completely inadvertent, and probably unbeknownst-to-them) technical violation of the GPL. In fact, one could put such a site (or someone's web site, if they had an ftp client which allowed uploading) in technical violation, it seems, by placing a GPL-licensed binary there but not the corresponding sources and waiting for someone to download it.
Sites like download.cnet.com circumvent this issue by not hosting the downloads themselves, but by directing the user to the developer's site.
Here's an interesting question to ask: the Apple iTunes App Store and the Android Market don't really require or support the uploading of source code as part of placing a program for sale in their respective stores. They don't support the downloading of source associated with an application which someone purchases.
So, if someone demands sources from them for a GPL-licensed program, having received a binary through the store, what are they to do? They can't provide what they don't have, and I'm sure they're not looking to become a repository for GNU code on the FSF's behalf because some third-party decided to use the GNU code in their own app.
Again, whether the source code is or isn't available from the developer makes no difference. In the FSF's view, since the store is where you got the binary from, the store is where you must be able to get the corresponding sources from.
It seems the app stores are left with two choices: change their procedures entirely around to support a very small number of (probably unprofitable) applications in the way the FSF insists, or simply disallow GPL-licensed applications from the stores entirely.
I predict they'll do the latter.
