Seems like this must still be in progress, their home page redirects to the new .ai domain but there are still a lot of pages that load on their existing .com domain.

Shame there's no blog post/article actually disclosing this change anywhere (how do we know this isn't a clone trying to steal market share or phish logins?)

The ifttt.ai page lists ifttt.com as canonical, guess that's a vaguely good sign (although it would have made it hard to submit to HN)