It _is_ the Yahoo! logo. paulgraham.com still runs on Viaweb, which is now Yahoo Store, which is probably where the favicon comes from.
I didn't mean to imply anything about the code or architecture of Yahoo! Store, just about its origin.
$ host 68.142.205.137 137.205.142.68.in-addr.arpa domain name pointer html1.store.vip.mud.yahoo.com. $ host 216.252.126.190 190.126.252.216.in-addr.arpa domain name pointer html1.store.vip.sp1.yahoo.com.