Unfortunately I think people have a tendency here to downvote comments they disagree with rather than weighing them on their merits. Although I concede that perhaps it had something to do with the Nazi stripper comment ;)

I completely and unequivocally disagree with almost everything you said, though. I’m not entirely sure whether you’re speaking legally or on the level of what you think the company ‘should’ be doing from a moral perspective, but I think you’re speaking from a moral perspective.

But you’re attempting to say that the price does not matter, and here you can’t ignore the legal aspect, because price most certainly does matter in that respect. If you are paying for the service and there is therefore an actual honest-to-goodness contract between you and the business, then they do have a responsibility to continue to provide the service as stipulated in the contract. However, even then, it’s common for businesses to stop providing a service; if, for example, they refund your money. IANAL, but I imagine the Uniform Commercial Code provides for this sort of eventuality. Look at Lala shutting down: Apple decided to entirely remove the service off the face of the earth, leaving users entirely out in the cold. And they didn’t even refund anyone’s money—they just gave out iTunes gift certificates. I personally don’t think there’s anything wrong with this: they are making calculated decisions and they need to be free to make these decisions. Users must have an implied underlying understanding that the business may make changes like this.

But in the case of Posterous no monetary consideration is even changing hands and so the obligation is necessarily far more nebulous if there is one at all.

‘Sure,’ you’ll say again, ‘but I’m not talking legally, I’m speaking morally.’ OK—I’ll say again that I don’t think a business has any obligation to live up to whichever crazy expectation you happen to have dreamed up concerning their free service. Whatever your particular understanding of the service you are getting happens to be is completely orthogonal to what the business is going to decide to provide. If there’s one crazy guy in Butte, Montana who thinks Posterous is a dating site, and then Posterous decides to remove avatar images from the site, the guy in Montana just can’t complain that Posterous has ruined his ability to use the site as a way to look at pictures of potential dates. It’s their product, it’s their right to make any change they want.

Businesses, and especially web startups, need to be free to stay agile and change direction on a dime. They need to iterate to find a business model that works. Just because they were doing one thing in the past, people have no right to think the business is therefore forever after obligated to continuing doing so in the future.

I do think that it is absolutely within Google’s rights, if it so chose, to start charging money for Gmail tomorrow. It may break an unwritten contract, but that doesn’t mean they can’t nor shouldn’t do it if they decide that it’s in their best interest to do so. You may say from a practical standpoint that they’d lose 95% of their users if they did such a thing. But they are completely free to decide to make a change that drives off 95% of their users. I assume they would have calculated that the money they will make from the 5% of remaining users is worth it. Gmail is a bad example, though, because obviously Google is giving away the service for free because it brings in tons of eyeballs on their ads. If ad revenue in Gmail fell precipitously with no hope of coming back, do you think Google wouldn’t really start charging for it or cancel it altogether?

It’s ironic that you talk about ‘unwritten terms’ between the business and user, because someone already posted the Posterous terms of service, and it explicitly says that they might do this. So there are no ‘unwritten terms’—there are written ones and they explicitly allow for this, so it’s moot.