The 3D acceleration is not supported on ESX (and VMware Server).
I notice the flag too, but there is no info in the release notes:
http://www.vmware.com/support/vsphere4/doc/vsp_esx40_u1_rel_notes.html
Maybe is for future implementation in View.
Andre
Andrew | http://about.me/amauro | http://vinfrastructure.it/ | @Andrea_Mauro
