The phpMyAdmin thing on Flattr has been around already for some time. I just created it together with other my stuff and somehow did not find time to discuss it with other project members and push it to our website. Despite this fact it got some attention and even recommendations.
Today, being pushed by Linus Olsson from Flattr (who just forwarded questions about authenticity of phpMyAdmin on Flattr), I finally find time to get an agreement from other project members and placed the button on phpMyAdmin's website.
Let's see how popular it will become now :-).