I did talk with Flattr when BIPS was in San Francisco. I will try and see what I can do to bring this to fruition.
Have them talk to Tony or Steve at BitPay and it'll be solve within an hour.

I helped Bit-pay more than plenty already.
there were very few providers that could guarantee transactions both ways. What I mean by this is users would load up Bitcoins, the provider would take those bitcoins and then give Flattr euros and finally when a user wants to withdraw on their Flattr account they would then get the option to withdraw in bitcoins.
I got a unlikely maybe from Bitpay, a unlikely maybe from coinbase, a "i think so" yes from Charlie Shrem with Bit Instant, and a maybe yes from a Sweedish exchange outfit.