Yes, they are. If you choose to restore a phone after backing up to your Google account prior, WiFi access points and their passphrases are restored, some display settings are restored (wallpaper, screen timeout). Oddly, there are many settings that are not restore which I think should be - phone ringtone, notification ringtone, etc.
You can go into your Google account dashboard:
https://www.google.com/settings/dashboard
Log in, and there should have an "Android" setting toward the top, with a triangle to the left. Open it by clicking the triangle (ths may be easier on aPC, by the way) and it should list all of your Androd devices, including a listing for "applications with backup on servers". You can't
see the backup data, but you can delete it all with a button press just below. For me, my phones (including my older phones, still there) have "Android System settings" (that's the WiFi and display stuff I mentioned before), "Android Market", and "Google". I don't play games, but I assume that if there were games that backed up data to Google, they maybe there, too (though maybe that's all collected in "Android Market").
Funny, they have the Play Store listed as the old name "Android Market" (which I think they should have kept.)