You do seem to have a lot of privacy concerns. I really have to ask why you'd want to put your photos on a public site, but not want them to be accessible by anyone.
Most of my photos are on my iDisk, inaccessible to anyone but me. A short few are on my MobileMe gallery. I didn't want people to see most of them (because they feature people I don't think would appreciate being online), so I kept them on my iDisk.
Yes, I do have a lot of privacy concerns, because the 'net offers a lot of opportunities for privacy to be compromised. If you "have to" ask, I guess I "have to" point out the assumptions you have made that would naturally confuse you here.
Apparently, you assume that I "want to put (my) photos on a public site, but not want them to be accessible by anyone." Where you got this idea I don't know, because I didn't say (or imply) it.
What I *do* want is to utilize MobileMe Web Galleries as a substitute for e-mailing photos to friends. It would obviously be much easier for my friends to see a lot of photos on a Gallery than it is for me to e-mail attachments to them.
Also, I have not been thinking of MobileMe as "a public site," mostly because it does offer password-protection for viewing of photos. To me, a password-protected Web Gallery is not "a public site."
Originally I had intended to use iDisk for this purpose (instead of the Web Galleries), but again, it's much simpler for my friends to visit a Gallery than it is or them to wait around for potentially rather slow downloads to arrive from iDisk.