Once costing $399, the service is now available free of charge. According to TechCrunch, the pro version lets you:

• Print images at 4800×3200; non-Pro is capped at 1000×1000.
• Automatically import a few thousand addresses at once to be pinned on a map
• Capture HD videos of what’s on screen.
• Measure distances/areas using lines, paths, polygons, circles, and more. Non-pro can only handle lines/paths.

Sign up via this form, then download the free Pro client. (Several commenters noted that they got an error message upon submitting it, but that re-submitting fixed the problem.)