Selecting 'About this mac' from Finder caused Finder to crash, and with it, all currently running applications. Restarting the virtual machine causes a kernel panic. I used the iBoot + Easybeast method developed by tonymac, but there were a lot of things that irritated me. I eventually ran across some sites saying that Core i users were having trouble using the EFI method and would need to use the standard hackintosh methods to run OS X on non Apple hardware. However, my new machine is a Core i5 (Sandy Bridge) and the 10.6.3 install disc wouldn't boot in VirtualBox. My old machine was a Core 2 Quad (Kentsfield), and I was easily able to install Snow Leopard in VirtualBox 4 using EFI emulation.
I don't like Macs well enough to use all the time, but I need one to build software for Mac. Although my machine is capable of being a hackintosh, it is usually easier to build software in a virtual machine which doesn't require restarting. I recently built a new computer and have been trying to get Mac OS X working on it. VirtualBox 4.1.24 seems to be the last version where this will work. Edit: 2013-May-23 - This doesn't seem to work with new versions of VirtualBox.