Release notes show that developers have implemented “extensions window & tabs API events.”
“The extensions posse would like to point out that as of today’s dev channel release, extensions are starting to be a bit more useful. We can now put little bits of UI (user interface) in the chrome of Chrome, and some of the APIs (application programming interfaces) are starting to come together,” said Google programmer Aaron Boodman. “There is still quite a ways to go, but if you’re interested in building extensions for Chrome, this might be a good time to start taking a look.”
You can download the latest developer release from the Chromium website.