In case you had not noticed, you can now log in to your ProZ.com account using your Google, Facebook, or LinkedIn credentials. The Google and Facebook options have already been announced here previously, in separate posts.
These log in options are provided to make it easier to jump to your ProZ.com account, or to access your account in the event of a forgotten password.
If you run a website or application and would like to allow your users the option of signing in with their ProZ.com accounts, you can find out how here.