Software Raid 5 work on ROOT ?

Hello every body.

I have a question in regard of booting linux under a raid 5. It is possible ?
All the guides that I found on the net say to have a /boot not stripped, (raid1
is ok). [EX: http://www.gentoo.org/doc/en/gentoo-x86+raid+lvm2-quickinstall.xml
]

They say to have / not stripped too. And these guide show to have an raid 1 boot
and / and create a LVM volume for /usr /opt /var /whatever that can be raid 5.
It is not easiest to have directly / in raid 5 format ?
If it's possible I would prefere to have raid 5 /
There any particular configuration for grub to boot it?

Thanks in advance.