installing virtualbox-ose-guest-x11 in the natty guest worked great for me, I have 3d accelerated 64bit Natty and Unity working within the 4.0.4 virtualbox on a 32bit Maverick host
installing virtualbox- ose-guest- x11 in the natty guest worked great for me, I have 3d accelerated 64bit Natty and Unity working within the 4.0.4 virtualbox on a 32bit Maverick host