GMail/Picasa Identity Leakage
Be careful when using Picasa and other Google applications with default nickname and web address settings, since the number that Google assigns to your ID in those cases is easily decipherable. The number is just a replacement for your ID and is consistent, not random. This is not a new issue, and rather old, but I still see a lot of Picasa links that have those numbers in them. Without changing the defaults, an attacker can replace the URL in a page with javascript:alert(_user.name) to obtain the relevant ID. Read more in this Lifehacker article. Continue reading GMail/Picasa Identity Leakage