iOS 4 - Can I close an app without it staying open in the background? I am aware that after closing an application (pressing the home button) you can enter the multi-tasking tray, hold your finger down on an icon and close an application properly. But is there an easy way to perform this series of actions with one command? Sometimes I close an app and know I will not be using it again any time soon and would not like it to remain open in the background.
Not presently.

iOS multitasking however is quite different than say the multitasking in Android or Mac OS X. The app unless it specifically is using one of the 7 methods to run in the background is "frozen" and won't consume any resources until it's brought back to the forefront. Essentially the fast app switching feature as part of iOS 4.0 is a large part of why you saw so many apps being updated to work with iOS 4.0 multitasking.