Has this changed in JB from ICS?
I ask as I'm wondering if you're referring to the "recent list"... swiping an app from there doesn't necessarily kill it, it only removes it from the displayed list of recent apps (notice the current app is never listed). It's either already dead, or still running after you swipe it away. To actually stop a running app is a royal pain in android, requiring you to launch "settings", scroll down to apps, select the "running" tab, scroll though the list of apps and services, select the one you want to kill, then click "stop". Kind of a pain, really.
That's why there are so many app killer apps out there.

What you've described, however, sounds exactly like WebOS... to kill an app, you just fling it off the top. You can also pull down like stretching a slingshot's bungie and shoot it off the top. The TouchPad even has an Easter egg when you do it upside-down. Maybe the Jolla guys will borrow that from OpenWebOS.