GM's relationship with its subsidiaries differs from (say) Aston Martin/Ford greatly. Aston Martins are not sold alongside Fusions at my local Ford store, whereas Saab is sold alongside Saturn. My point was that Saab is a recognized domestic brand (as a subsidiary of General Motors), while other relationships (like Ford/Mazda) are not nearly so prominent. Ford and Mazda each have their own isolated dealer network etc., and are for all intents and purposes different companies. It is not uncommon to hear someone refer to a Pontiac/Chev/etc. as a "GM" - I have yet to hear someone call a Mazda or Volvo "a Ford". Saab (and all of GM's holdings) are much more integrated into the main company, to the extent that we see massive rebadging of GM vehicles (like the Saab 9-7X). So in talking about import vs. domestic brands, I would call Saab a domestic brand (although, admittedly, it begins to stretch that definition). The thread titles does cite imported vehicles, though, so while technically correct, all of a sudden doesn't really say a lot about the manufacturers.
All said, pointing out that GM builds a lot of its cars overseas and Honda et al. build lots in North America on this forum is like pointing out that the sky is blue.
