The GPL requires that anyone who receives the work also either receives the source for the work (the preferred form for making changes), or...
Not quite; it requires that anyone *given* the work is also *given* the source... as you note below, they can decline to take it.
>If he declines to take the>source, he can't pass it on (unless he wants to sign up for the >three-year offer or somehow obtain the source).
Actually, the first sale doctrine applies. He can pass it on, he just can't pass on a *copy*.
If he wants to pass on a copy, he can darn well find the source or the written offer (since he was offered one of them).
>You might want to add an exception to the GPL for your documentation, >saying that a distributor is exempt from including source if they >leave in a notice saying where on the web the latest source can be>found, otherwise they must fully comply. The license would still be >GPL-compatible.
Perfectly reasonable exception, although I'd add that the distributor should guarantee that the source *can* be found on the web at that location for three years. ;-) Which gets us pretty close to the written offer again....