My big unanswered question going into the article was "What the crud is Flattr and why should I care." Starting your posts off with a brief introduction of who you are is often a good idea.

Flattr is a micropayment system. You pay them a monthly subscription, then Like(tm) a bunch of stuff on the internet. They split up whatever portion of your monthly sub that they don't keep among the places you tag. Apple presumably flagged the app which integrated Flattr due to their well-known policies about in-app payments.