I think I found it: (should have read Dart’s FAQ first, instead of googling “GWT vs Dart”)
From: http://www.dartlang.org/support/faq.html#future-for-GWT
Q. What’s the future for GWT?
Bruce Johnson posted on the GWT blog (with further comments on Plus):
“Dart and GWT both share the goal of enabling structured web
programming. In fact, many of the same engineers who brought you GWT
are working on Dart. We view Dart as an ambitious evolution of GWT’s
mission to make web apps better for end users, and we’re optimistic
about its potential. As Dart evolves and becomes ready for prime time,
we anticipate working closely with the GWT developer community to
explore Dart.”“Meanwhile, rest assured that GWT will continue to be a productive and
reliable way to build the most ambitious web apps—and even games like
Angry Birds. Key projects within Google rely on GWT every day, and we
plan to continue improving (and open-sourcing) GWT based on their
real-world needs.”