That's sort of bad gouge. Most apps shown in the "multi-tasking bar" are suspended, not running and not draining the battery. Some apps may stay open for up to ten minutes to complete a task, others may register with the system to keep some specific services open in the background.

Apps such as Skype and Pandora will in fact be running in the background, which you may or may not want. If you aren't concerned about receiving calls via Skype, than closing it as indicated by the original poster will save battery life. Very few apps keep services running and most that do probably do so for a useful reason that you would be defeating by closing them.

That's got to be worth two cents.