That's very interesting.
Although people will come in here and say stuff like "Multitasking doesn't use any CPU cycles!"
It doesn't use cpu cycles. Unless it literally is an app that is multi-tasking.
Just because it's in the multi-tasking bar... (by the way it's not a multi-tasking bar, it's a quick switch bar) doesn't mean it's multi-tasking.
There are only a few ways that an app can be multi-tasking.
1) Audio - Pandora and MLB At Bat are examples of this. You can see it's multi-tasking by the Play button in the top right corner of the screen. Same thing the iPod app does.
2) GPS - TomTom, and Navigon are examples of this. You can tell those are multi-tasking by the arrow-like compass icon in the top right corner, same location the play button is in for the previous example.
3) Task Completion - Applications like Flickr could for example be uploading a photo. Pre-4.0 would quit the process if you left. In 4.x you can click home and leave the app. If the app supports it, the upload could continue for up to 10 minutes (or until complete) before the OS kills the app.
4) Voip - Skype is an example. You can see these apps are working in the background because of the red bar at the top of the screen.
You don't see any of those? Then nothing is multi-tasking. The only one you cannot see is Task Completion and it has a time out of 10 minutes, then the OS kills the process.
Anyone who is telling you otherwise isn't understanding the system, thus, don't believe them.