Unfortunately your faith does not serve you.
I spoke to a MobileMe Support Chat person last night to find out that they had scrapped the feature, at least in the current iteration of MobileMe and the product feature page had been edited to reflect that. I was reminded that the TOS Agreement allows them to do what they wish with anything (sounds like more than one Apple product launch to me, with announced features disappearing without a peep).
I then kindly pointed out to her (her name was Kara, but I'm pretty sure that they are all called that because it was the fourth time I had gotten a hold of "Kara") that the MobileMe support page still had instructions on how to use our now killed share button feature, and she told she would make sure to pass it on for removal.
So yeah... That's not very nice. Oh well, maybe our nigh $100 a year will justify future features, or in this case previously shown and announced ones.
Just before anybody says this feature isn't that important, it's the ONLY way that people could have shared iDisk files without having to use the web interface, or network shares, or through the finder. That would have greatly sped up the process of getting out files as you'd no longer have to worry about email attachment limits and the like, and I'm sure many people can think of scenarios where this would have been useful.
Oh well.