I have an Asus 1000H, it has a built-in webcam Chicony CNF7129.
Virtualization Software: Virtualbox 2.0.6
Host OS: Windows XP SP3.
Guest OS: Windows XP SP2.
Result: The webcam device doesn't work (Guest OS).
I have to mention that the problem is present only with my buit-in webcam Chicony CNF7129.
I tried with other external USB webcams and all of them work without any problem (Guest OS).
VMware Server 2.0.0 built 116503, seems to have the same problem.
http://www.virtualbox.org/
http://www.vmware.com/