Gnome 3 and Optimus technology

Hi ,

I'm using a netbook (asus N55SF) equipped with Nvidia Optimus technology ( 2 Graphical cards (intel and Nvidia GT 555M)).
I installed Ubuntu 11.10 on my laptop . First I had a problem to install it , so I turned acpi off to complete the installation .

But it appeared that Nvidia graphical card always causes a problem .
At the beginning , without installing Nvidia drivers and running only with Intel graphical card , Gnome3 worked well ( with acpi off wich is very risky to the hardware ) .

So I installed Bumblebee and Nvidia drivers ( acpi is turned on this time ). The boot process works fine .
When the connect screen appears ,that's when troubles begin , login screen displays many options to begin the user session ( Gnome , Gnome classical ...)
But all of them lead to the same thing , a User interface with Gnome 2 classical menu , with no window effects and shortcuts to switch workspaces are disabled .
Even the Ubuntu tweak changes does not take effect .

What changes should I do to fix the problem ?