Bert, your facebook profile ID is in that URL (the number starting with 1389...).
Also, there is no restriction on who can see pictures when you a direct link to an image. This is mostly due to the fact that CDNs used to store static files usually don't send cookies and thus have no concept of a session.
My personal portfolio site is listed in my HackerNews profile, on my portfolio site I have a link to my Facebook profile (so that people I give my business card to are able to more easily find me, and not my dad).
I am familiar with what is in the URL, and I am also familiar with CDN's. I was merely posting my rebuttal to the OP who said it was obfuscated.
https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-snc4/148199_...
Just for reference the picture should be this:
http://imgur.com/UYs6H
Oh ... the way I uploaded that to imgur? Using that URL above, so clearly that is wide open to the world.