Clubman - There are some rumours around that the next OS release will feature a virtual machine so you can flick from one OS to another, this is only a rumour though.
I think it's a move to get the hardware sales of Apple up. Their target is 10% market share. Quite an acheivement if they manage it as their current market share is only around 2%.
I'm not a Mac software fan but I like their hardware - being able to run both OS' makes their machines a viable alternative to Dell, Sony et al.