opkg: Fork of ipkg lightweight package management intended for use on embedded Linux devices;
ipkg: A dpkg-inspired, very lightweight system targeted at storage-constrained Linux systems such as embedded devices and handheld computers. Used on HP's webOS;
Wikipedia has no dedicated pages for either of them. I guess they're quite niche.
He says it was unexpected but it's been being talked about on the GitHub for quite some time now. It was really just a matter of when they decided to do it.