It’s available now, but it does cut support for quite a few Macs that Big Sur still supported.
Monterey feels of a piece with maintenance-mode macOS updates like El Capitan or Sierra or High Sierra—change the default wallpaper, and in day-to-day use you can easily forget that you’ve upgraded from Big Sur at all. It’s not that there aren’t any new features here—it’s just that improving any operating system as mature as macOS involves a lot of tinkering around the edges.
But there are plenty of things to talk about in even the most minor of macOS releases, and Monterey is no different. The update refines the Big Sur design and rethinks automation and what’s possible via local wireless communication between devices. It also makes a long list of minor additions that won’t be exciting for everyone but will be interesting for some subset of Mac users.