On Tuesday 10 Mar 2009, Siddhesh Poyarekar wrote:
[snip] I would have thought that third parties would mean people you distribute the modified software to and not the entire world.
Precisely. Your only obligation for source is to people who directly got the software from you. You are not responsible for providing source to a III-party who got the software somewhere downstream from your distribution.
However, since the licence is transferred along with the software, if FOO redistributes your software, then FOO is liable to provide the source to people who got it from her, ad infinitum.
Regards,
-- Raju