I am having a total mental block trying to recall the name of the "Donate people money through Twitter" service that was on HN a few times, but I think this is what he meant when he said "Do not take payments lightly."
[Edited to add: Tipjoy. I knew it was T-something but I ran through about 15 combinations of Twit-X before realizing that it was not from that naming convention.]
They were. Ivan's now at Facebook, where everyone assumes he's working on Facebook Payments. Abby's probably doing something even cooler, although IDK.
BTW, Tipjoy never held the money; they were just a front-end for PayPal, so they didn't have the issues that Fundable apparently is having.
[Edited to add: Tipjoy. I knew it was T-something but I ran through about 15 combinations of Twit-X before realizing that it was not from that naming convention.]