How 3D driver dependent are Unity & GNOME 3 ?

One of the major “selling points” of Linux has been its ability to run on older hardware, and I’ve seen enough people getting slightly hot under the collar about dropped support for older graphics cards (myself included)… with this in mind…

I know there was supposed to be a Unity 2D… is it included in 11.04 ? … and has anyone tried it ?

Same goes for GNOME 3 … as with Unity, I hear it defaults to a “classic” desktop if the hardware/drivers aren’t 3D capable… is this true ?

Considering Linux seems to be first tested by new users on older hardware, I would like to know how well Unity 2D works and if GNOME 3 has something similar.

After all, didn’t we all laugh at/get annoyed by M$ Vista’s AERO for this very thing.

[EDIT]

Another question…

If (and i mean if… I haven’t tried them yet) GNOME 3/Unity require a hardware upgrade to get the full effect of the new interface… WHY ?

What I mean is, why did KDE 4 not require a hardware upgrade, and why where the early versions of Unity 2D listed in a PPA as Unity (Qt):

Is the Qt framework doing something “better” than GNOME ? … is this the reason for the inclusion of the Qt framework ? … as previously stated KDE 4 didn’t seem to require hardware upgrades, and that seemed to have much more “eye candy” than KDE 3.5, specially when compared to the difference in appearance between GNOME 3/Unity and the earlier GNOME 2.x ???