The standard for PPP over Ethernet is L2TP. The pre-standard proprietary
implementations were L2F and PPTP, from Cisco and Microsoft, respectively.
I believe you'll find Internet Drafts on all three.
The idea is neither "highly bogus" nor used in association with 10Base-T
cross-over cables. It's used to tunnel ATCP, IPCP, IPXCP, et cetera over
IP.
-Bill Woodcock