Since none of the US versions of the Galaxy S have Gingerbread yet, I would think that it would be a Samsung issue. If you speak to them on twitter they always have the same canned answer "follow us, when we have more info we will tweet".
No, that would be a pretty clear indication that it's a carrier issue.
The international I9000 and Captivate are so similar that you can run I9000 firmware builds on the Captivate. Thus, there is NO way the Captivate Gingerbread delay was Samsung's fault - it was 100% carrier delay. There were a few Captivate-specific things that didn't quite work perfectly if you did a straight port with no customization - but there aren't enough differences to justify the delay.
Samsung had NO update frequency problems on the I9000, nor are they having any with the I9100 (International GSII). It's clearly a problem specific to releasing on US-based carriers, especially AT&T. Did you know that AT&T was the only U.S. carrier not to release Froyo for ANY phone in 2010?
Yep, seems to be more carrier delaying the updates to customers rather than a manufacturer. Especially when yo usee other customers already updated that are not with the same carrier as you. Negotiations are going on at the expense of delaying the update. By the time we get it, its already practically out-of-date