<<As of today, it is possible to sign in to Panoramio with Google Accounts.

Why are we doing this?

Last year we worked hard to integrate Panoramio with the Google infrastructure. Now that this is done, we can focus on building new features for the Panoramio community. Some of these features require Google Accounts, and we launch the new registration process now so that users can upgrade their accounts in advance.>>
http://www.panoramio.com/blog/sign-in-to-panoramio-with-your-google-account/