CrashPlan's top-bar icon, how to get it?

Are you sure you've checked the option to show it in your menu bar?

An alternative more direct way to access the Crashplan menu bar item is to directly launch it from within the Crashplan.app bundle.

It's located at /Applications/CrashPlan.app/Contents/Helpers/CrashPlan menu bar.app

I frequently exit the menu bar and re-open it to check Crashplan's status because it's much quicker than launching the full app.

I believe this icon was added in a recent update. It should update automatically, but in my machine something went wrong in the automatic update, and my Crashplan silently stopped running (I only discovered because I received that e-mail saying no backup was made in the last 3 days). Restarting my machine fixed the problem, applying the update correctly. After that it started showing the menubar icon.

One way for you to check if that's your case is to run the Crashplan app. If it freezes in the green logo with a "Upgrading" text, you should reboot your machine.