I'll definitely agree about the photos -- Japanese people with foreign friends or who have been abroad are also much more aggressive with the photo tagging.

I wonder how much of that is just Facebook, though; when I started using Facebook heavily about a year ago after having an account since the beginning, I was completely lost about how to upload/tag/organize pictures. Facebook wasn't much help with its cluttered interface.

As far as self-consciousness, I don't think it's necessarily a Facebook thing... Mixi users are just as self-conscious and "groom" their profiles to be just-so -- the same for their profile pictures, which are their public face. I would argue that it's more a facet of Japanese society than of Facebook in particular.

I sort of think that the Japanese Facebook population of frequent users is still a bit too small to judge, too...

Edit: I meant to say this before, but mobage and gree are both much, much more popular with people under 18 than adults in my area. I wonder how much of that has to do with the commercials.

Edit 2: I just realized this, but I wonder how much of LinkedIn's lack of popularity has to do with the conservativeness of business culture in Japan in general. I mean, they have standardized forms for resumes and personal history here.