Google have started updating Nexus One phones to Android Froyo OTA this past week. If yours isn't update yet, wait for the update notification, Or if you want to get you hands down the update yourself just follow the directions: Manual update instructions: » Download official Android 2.2 firmware for Nexus One » Copy file to your microSD card and name it update.zip » Power off your phone » Hold down VOLUME DOWN button & power it back on » phone will now search for files like PB00IMG.zip, etc. This's normal. Scroll down to recovery and press POWER button » When you see "/!\" symbol, press POWER button and Volume Up button at same time. You should be presented with a menu and one of the options should be "Apply sdcard:update.zip" » Use trackball to navigate to "apply sdcard:update.zip" and select it » When you see "Install from sdcard complete", select "reboot system now".
You can install Adobe Flash Player 10.1 for Android, see it in action: