There’s been a lot of discussion out there about Readability’s original plan to distribute 70% of what the users paid to publishers, how much unclaimed money that plan ended up with, and whether Flattr solves that problem. One aspect that hasn’t been sufficiently clear is their different methods of allocating money.
Under Readability’s now abandoned system, if you signed up for $10/month with $7 of that going to publishers, and you read 10 sites, your $7 would be allocated to all 10 sites, that presumably get 70 cents each. If only 2 of those publishers actually signed up to be paid, then only $1.40 would be paid out, with $5.60 left unclaimed. That $5.60 will now be donated to charity.
In Flattr’s system, if you pledged $7/month, that $7 will only be allocated to sites that actually signed up for Flattr. If you only visited 2 sites that have signed up for Flattr and clicked the “Flattr” button, they would each get $3.50. This leads to a more skewed distribution of donations to sites, but no unclaimed money.