Quoting a post on the mozilla.dev.platform Google Group:
e10s is a priority for Mozilla’s engineering management and they are dedicating more help to make it happen. We’ve picked up some Firefox Metro engineers looking for new homes, new engineering manager, a Google Summer of Code student, and a gfx contractor. So expect to see more progress and more review requests.
You can check out recent improvements in Firefox Nightly:
You can test e10s in its own window, like Private Browsing, using the Nightly channel’s "File > New e10s Window" menu item.