Every Smartphone comes with certain pre-installed apps that you might not necessarily desire. But facebook certainly never was one of them. At least none of the Samsung series comes with it.
I just purchased a Motorola Defy XT from Republic Wireless and it came with the Facebook app pre-installed. I immediately checked for a system update (which there was one waiting), installed it and the FB app went away. Usually it doesn't work out that nicely though. My last Android was the HTC EVO and you couldn't get rid of FB unless you rooted it your phone.
The Google Nexus One had Facebook force-installed; (I think) it came with one of the OS upgrades, which is even worse than pre-installed, because I really had no choice.