First of all cheers for the tutorial. I learnt heaps even though i couldnt get it to work! Because the partitioner would not see md0

The reason why it failed for me is.

mkfs.xfs /dev/md0
ln /dev/md0 /dev/sde

When installing from ubuntu server cd.

The trick is in a system recovery or live cd command prompt to type

mkfs.ext3 /dev/md0

Instead (dont bother with ln /dev/md0 etc)

This formats the raid array in ext3 which unlike xfs can actually be seen by the server installer!

Now when in the partitioner you select manual setup. At first you still wont see md0 but fear not! Setup your boot partition (/dev/sda1) and your swap partitions (sda3 sdb2 etc) then go into configure software raid. Now click finish (if you click on delete raid array youll see your md0 array! yay! But don't delete it of course!). Now when back in the partion screen you will see the md0 partition!!! yay!!

Now change it to use as ext3 with / (root) but dont format

All done!