How do you install Google Play?

[Bateluer]

I think my phone was fairly molested by the last owner. When I found out how to get to recovery mode, I reset the phone to factory settings. Surprise, google play was preinstalled on factory mode, as it should be for android 2.2

On older phones, Android Market should upgrade itself to Google Play fairly quickly. Thats probably what happened when you factory reset, when you signed back in and started the Android Market, it prompted you to upgrade and accept updated terms/conditions.