@gsgleason: It is rather well known that the speed which you talk about, that is switching between screens etc, is mainly due to something called KMS (Kernel Mode Setting). Mode setting is done by this same driver (Nouveau), which loads at early boot and also handles the boot graphics. Also try changing resolution or handling multiple displays using a xrandr application like krandr in KDE. It is super fast. What's more awesome? Switch to text mode (ctrl-alt-f1 to enter and ctrl-alt-f7 to return to X), and watch some text scroll (say run 'dmesg') and it is blindling fast. (With Nvidia driver or any non-kms driver, it will take more than 10 seconds to scroll by.)
@ gradinaruvasile and gonzo_s: Video (XV) is very good, can handle 1080p. Flash is (hence) very good too. In general, 2D and basic stuff are as good as good as you can get. 3D is getting there. It is pretty awesome in the mesa-experimental branch (which should eventually become 7.9). Try installing mesa from xorg-edgers ppa repository. (Oh, I am using Gentoo and mesa-git. Also, my notebook graphics card is 9800M GS which is very powerful.) Quake3 runs silk smooth (but thats a 12 year old game) and compositing effects in kwin work well too. It is commendable for a reverse-engineered driver. There is possibly very little or no power management, so card will run hot. (Very hot in my case.) The only reason I don't use is because I do use OpenCL and CUDA for GPU computing.
@AaronP: Can you please confirm if Randr 1.2 support is ever going to come in Nvidia drivers. Even some of the simplest of drivers support it. The multiple screen management in Nouveau is so much better. The biggest issue being that Twinview still gives a single huge 2560x1024 desktop instead of two 1280x1024 desktops for example. And it is useless for full screen applications. At least provide a mechanism to do that in nvidia-settings. (I don't want to do that using xorg.conf on a notebook that connects to different external displays all the time.) Any form of KMS would be awesome too, but I assume the bog standard reply would be that mode-setting mechanism is proprietary (which strangely the nouveau driver has it done better anyway