Now Anyone Can Download Photos for OS X Beta with OS X 10.10.3 Beta — For Free
If you just can't wait to get your hands on Photos, now's your chance. Apple has opened OS X 10.10.3 to a free public beta.
Just be sure you don't install this on your primary system. It's a beta operating system after all; you have no idea what other apps you rely on every day will or will not work here. That's why I've tagged this photo “Advanced”—beta isn't for everyone!
Head over to appleseed.apple.com/sp/betaprogram to sign up and start downloading. Enjoy!