No, xmpp.org is the XMPP Standards Foundation. The Modern XMPP project is a separate initiative.
Well, as separate as can be - I'm heavily involved in the XSF as well. But the XSF is focused on matters of protocols, and it grew increasingly clear to me that we needed a less official space for collaborating on non-protocol issues such as user interfaces.
Fosstodon is an English speaking Mastodon instance that is open to anyone who is interested in technology; particularly free & open source software.