Due to the Galaxy S only sporting 512MB RAM, Samsung stated it was impossible to update these devices to Ice Cream Sandwich without sacrificing TouchWiz and associated applications. While many geeks would say "good riddance!", the fact of the matter is that offering an upgrade that removes said applications is not going to go down well with consumers, opening Samsung up to all sorts of legal nastiness.
So, assuming this is indeed true, I can somewhat sympathise with Samsung's initial position.
Still, the Galaxy S entered the market only 18 months ago, and the Galaxy Tab 12 months ago. Cutting these expensive devices off from support so soon is simply bad business sense, and the backlash on the web was pretty huge. The usual petitions, angry Android fansites, and so on; they do seem to have helped.
Korean websites are reporting that Samsung is reconsidering its position due to strong consumer demand, but that it still needs to find some way around the 512MB RAM limitation. My suggestion would be to offer a TouchWiz-less upgrade to ICS, but make it optional - so that those that know they're getting stuff taken away can agree to it specifically.
For now, there's nothing final, but I highly doubt Samsung would let it out they're "reconsidering" if they're not going to actually, you know, reconsider.