no, I think that was slush's pool that returned the accidental 100 BTC transaction fee (the original thread was here on Bitcointalk, cannot remember when though). P2pool would've been a nightmare to get overpaid fees refunded, there were usually 100-200 payouts per block, where the 50 or 25 BTC reward (don't think p2pool survived past 12.5 BTC) got paid to that many addresses. They'd all have to have been paying attention (and be sympathetic to the mistake too) to refund it all! Slush's pool is still pretty big last I checked.
In 2011-2013 there were more pools that did that as such mistakes were common (I would dare say depending on the payment method employed the vast majority of pools would try to return the money), including at least one case when individual miners returned a substantial percentage of bitcoins lost to an erroneously high fee transaction from a P2Pool block. Back then most people hanged out on bitcointalk and on several freenode irc channels so it was easier to reach a large percentage of the community. I mentioned P2Pool as an extreme case, IIRC that person was lucky that several larger miners returned the extra coins they made from that block, in another case less less than 10% were recovered but there were way more miners working on that block (399) after Bitcoin has attracted a lot of people during the two rallies that year:
https://old.reddit.com/r/Bitcoin/comments/1syu3h/i_lost_all_my_bitcoins_in_an_erroneous/?sort=newAFAIK there are very few cases when user send Bitcoin to wrong address or spend too much on fees and got their Bitcoin refunded.
I've heard of quite a few cases, so unless you put effort into making a well-sampled poll, you won't know what are the odds of getting the bitcoins back.
And if someone has sent bitcoins to a wrong address, that's also often rectifiable if it's someone they know well enough, or a non-scammy cryptocurrency company (exchange, gamblign website, whatever), you just have to contact them. It's not the same thing as sending to 1BitcoinEaterAddress(...).
