Yep. EverClip operates in the background. And not just for Safari. Any content that you copy in any app will get clipped to EverClip. Once there you can select one or more clips in the EverClip app and send them to Evernote as a note.
Hold in mind that because of Apple's limitations on background tasking, EverClip times out if you don't use it for a while. It will warn you with a popup notification when it turns itself off. And you won't hear the beep each time you choose copy, of course.
Hold the boat!
Looks like there is an iPad version of EverClip now. Looks like it just came out a few days ago. Or I just managed to miss seeing it before. One or the other.
I'm off to buy it.