You should share the forms to people as 'Reader' this way they can only see the Responses and the Summary Report. You can easily removing them from the sharing list if you don't want them to have access to the data anymore. This mean that all these people will need to have a FormsCentral account (it can be a free account). You will have to un-publish your form to prevent any other people to see the data.
Hope this helps
I'll take that as a "No" in answer to my question then!
The problem with asking everyone to sign up for a FormsCentral account means they get harrassed by unwanted Adobe emails for the rest of the Millenium (whatever privacy is set)!
It also requires them to learn their way through FormsCentral to read the reports.
I doubt I will be the only user who encounters a problem with 'Collaborators' who resign and cease to be authorised to view assembled data.
Unfortunately there is only one public public link per form. If you want to have full control on who can see the data you will need to share the form with them especially since there is nothing preventing people to share your published link to anyone.
The experience in FormsCentral for the anonymous user (published form) and the Reader is basically the same. The only difference is that the Reader has an Option Tab so that he can receive email notifications when new responses are received. They besically only have access to the "View Responses" and the "Summary Report" like your pushished form.
You can create an idea for what you are looking for : http://forums.adobe.com/community/formscentral?view=idea (click on "Create an idea" in the top right corner)