Wayne-
Why does tha satalite photo freak you out. If you have my address, you can stop by...no need to use a satalite.
A satellite photo of my backyard doesn't freak me out. It's the fallacy that many people hold that simply because they are on the Internet using an alias login that they are invisible and they don't need to be protective of their personal information, gun serial numbers included. Personal information is like dominos: once the first bit is derived, the next detail falls, then the next, and so on.
Without going into exactly how this is accomplished, suffice it to say that
no one has to have your address as a starting point to get to your house. Simply playing with information publicly available to the "average Joe" on the Internet can yield a set of driving directions to your house, and detailed pictures of your landscape (complete with trees and out buildings).
Generally speaking, may people are surprised at the amount of information that is freely available, hacking and screw ups (e.g. the ChoicePoint fiasco) notwithstanding.
If you go to your county's web site, there is a good chance that you can look up your own ( or your neighbor's ) property tax assessment including lot size, square footage of house, and taxes paid over the previous years. If the county doesn't have this, one can whittle away at the lexis-nexis database (although you must pay for some services).
I don't know if anyone here recalls this, but several years ago, the Edgar archives (SEC Filings Database) provided Bill Gates social security number on one of Microsoft's public filings. While this is arguably one of the richest men of our time, he didn't know his personal information was available until it was misused.
On a dare, I was able to give a teacher with an unlisted phone number information about his last 6 cities of residence (over 3 states), his current address, round trip mileage to his job, and the name of his subdivision block captian. It took less than 20 minutes and I didn't pay a dime. Although I didn't provide him with the satellite pictures of his back yard, believe me, he was very freaked out.
YMMV.
All I'm saying is that the same thing is possible with posting a picture, or posting an opinion, or doing anything else on the Internet. If someone wants to afford themselves the privacy of not showing their serial number, one has to respect that.
And while I think we all already knew that a picture I post of a gun on the net can be traced to me...the real question is whether it is a big deal or not that others know my gun's serial number. If you knew my car's VIN number...so what? My gun doesn't have any credit cards or bank accounts to steal. Knowing it's number doesn't somehow make you the owner....so just what's the big deal?
Your gun serial number is very much different from your VIN. As an example of "worst case" abuse, let's suppose that someone who didn't like you very much was able to acertain that you had an R9 serial number "Rxxx". Agreed, that in itself is no big deal. Now let's take a big, scary step further. That person calls the police and states the following:
"I was threated at gunpoint by [insert your name here]. He was even so brazen as to stick the gun in my mouth and shout at me while I was held here for hours. I was so terrified for my life that I'll never forget the serial number Rxxx. That's why I called 911. Thank God you're here!"Now I think we can all agree that this is not a situation any of us would want to have to defend, so why take the chance? Now I'm not a police officer, but I would imagine the first order of business after you are taken into custody will be to verify the story by checking for an R9 with the matching serial number. After that, I imagine it's pretty much an uphill (and expensive) climb for the defense. And, granted, that's a pretty extreme example. But again, I'm not the most sinister mind in the world, so I'm sure there are others who can do much worse.
While I am a faithful supporter of the Constitution, I'm not sure how it is going to protect me in this case. In this example, I have sowed the seeds of my own demise by unnecessarily providing too much personal information. While I agree with Richard that perhaps knowlege by others of what guns I own isn't necessarily a bad thing, I don't believe that anything good can come of offering a published record of owners to serial numbers.
By the way, this doesn't have so much to do with the Constitution, but rather the freedom of information. Where this may become a constitutional issue is in what is done with the information by agents of the government.
Keep in mind, all of these examples utilize civilian systems, -the government can do much better! Use prudent judgement in what you chose to publish for all the world to see.
This is precisely why I keep my NRA dues paid, and my personal information close to the vest. 
