closing all background apps (multitask) without jailbreak (cydia or else)

There are no apps that I know of that will close all running applications.

Is there any app to close all apps in the multitaskbar without the jailbreak.

No - third-party apps cannot control other Apps.

But why would you want to do this? iOS automatically closes apps if it needs to.

Perhaps this will help you understand multitasking on iphone:

http://whenwillapple.com/blog/2010/04/19/iphone-os-4-multitasking-explained-agai n/

Hi, there us a need fir the ability to close ALL apps at the same time. Just 30 minutes ago my iPhone 4g was burning up in my pocket... Running super hot. Know that the phone was processing something furiously, I close all 40 something apps "running" in the background, put the phone back in my pocket, and 15 min later took it out again and it was cool. Conclusions?

There were almost certainly not 40 apps running. VERY few apps run in the background. Read the link I provided in the last post.

The iphone has a recently used apps screen. The apps shown are most likely not running, they have just been used recently.

If the heat issue continues, then make an appointment at the genius bar.

I've just made an interesting discovery - Terminating an app in the recently used apps screen does not necessarily kill the background process that is associated with the app! I first suspected this was the case with Game Center, because my phone continued to use battery even after I "closed" it, until I went into settings and set a restriction on interactive games.

But yesterday I used the Yahoo Messenger app. When I was finished with it I closed it in the recently used ribbon. My battery still went down rapidly, however, and several hours later I got a "ping" and saw that I had an incoming message. YM still did not show in the Recently Used ribbon, but the app still appeared to be active. When I opened the app again and actually logged out my battery life went back to normal.

Very interesting.

This should be the case if the application is not running but you still have push notifications turned on for that app. So what is most likely happening is that the yahoo servers see you as logged on and will ping your phone. Unless you log off of yahoo's servers(as you did) then you are still going to receive notifications.

Except I thought Notifications were not supposed to require much from the battery. In the several hours between the time shut down Yahoo and the time I received the Notification (which contained a full message) the battery dropped like an anchor. From 80% to 10 % in about 6 hours, and nothing else was running. After I logged out the battery drain stopped immediately.

Yes. You need to download Bossprefs. I think its source is bigboss or something. Once you download it, swipe your finger from left to right accross the status bar. Go to Processes and then free memory or manually end them yourself. Then go back to processes after you exit and make sure that all were ended. Mail usually dont exit unless you turn push and fetch off in the legit ipod settings app.

Nevermind... You have to have JB for that.

and the problem with that is what?
it is not feasible...