It's a tricky area for Samsung, though. It's easier to market a single specific product with a single specific name. Droid droid droid droid... one name, one easy to remember catchphrase.
It can be argued that "Vibrant", "Captivate", and especially "Epic 4G" are all more compelling names than "Galaxy S", but the problem is that they're all different names, nothing to focus on. While Samsung is trying to get "Galaxy S" burned into the minds of the smartphone-buying public, T-Mobile is (lightly) pushing "Vibrant", AT&T is (even more lightly) pushing "Captivate"... I fear that only folks like us hanging around smartphone sites will make the connection.
I want to be proven wrong though, and a clever marketing campaign can overcome all of these difficulties. Samsung could highlight the fact that whatever your carrier, you can get the phone, all carriers are equal (some carriers are more equal than others of course

). They can only do
that though once all carriers have announced release dates.