Hi I found this on the Gizmodo website and it confirms your findings.
Multitasking is limited to audio streaming, VoIP and GPS apps, as well as a few other allowances: they can finish specific, important tasks in the background, for example. As far as non-music/nav/VoIP apps, those can be suspended in the background, but not left running.
I have skype and tried this whilst opening Gmaps. Quite disappointing
I've just upgraded to OS 4.0 on my iphone 3GS .
Main reason for doing so was the ability to multitask apps..
But multitasking doesnt seem to be working as I expected to.
For example, I am listening to music on the Spotify app or some internet radio app and would like to check my emails at the same time.
When in the internet radio app, I double tap the home button, switch to the mail app but then the music stops... if i switch back to the internet radio apps, it restarts like i'm starting it afresh from the main screen... So it looks to me that OS 4.0 "multitasking" is just a menu to quickly switch between apps but it doesnt allow apps to run concurently.
Am i missing something here ?
Also , what is this list of apps when you double tap the home button, is that a list of recently used app, or is that the list of apps currently working in the background ?
I couldnt find any official apple help on this.