ipMIDI is an informal protocol transporting MIDI using UDP multicast. So yes, it is a network transport protocol for MIDI. On the other hand, there is another network transport protocol called RTP-MIDI that has nothing to do with ipMIDI except that it is also a network transport for MIDI. Both protocols are totally incompatible.

What has this to do with MIDI.org? RTP-MIDI has been adopted by Apple long time ago and it is supported on all its commercial products. MIDI.org has always promoted this solution, probably because the money from Apple. And there is an article on this site talking about it. There are also RTP-MIDI implementations outside Apple, like a famous one by Tobias Erichsen. The standard was published by IETF (RFC 4696) although Apple does not follow the standard session management. See the wikipedia article for details.

In my opinion rtpMIDI is over-engineered and very uncomfortable for the users, to say the least. On the other hand, ipMIDI has only one commercial software implementation by nerds.de (there are also several hardware products) but it is extremely simple to implement and use it. There is no published standard at all, but several open source implementations are all compatible with the commercial drivers. See: qmidinet for Linux, qmidictl for Linux and Android, and also my Drumstick libraries and VMPK.

The MIDI Association is made up of members. Any member can bring their contributions to the other members where once it goes through the process it can become a MIDI standard. I'm unaware if ipMIDI has made attempts to do this (ipMIDI and rtp-MIDI were created long before my involvement - so who knows :))

However that being said the MIDI Association is working on a new Network Transport for MIDI 2.0. This new design should (in my opinion) be much simpler than rtp-MIDI.