Number 4 specifically states as follows:
The plugin must not embed external links on the public site (like a "powered by" link) without explicitly asking the user's permission.
While the plugin gives you the option to remove this if you read through all the settings, it by default injects this in the footer:
<a href="http://wordpress.org/extend/plugins/picasa-express-x2">With Google+ plugin by Geoff Janes</a>
Shame on you Geoff!
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