Sure, this is an easy process...
Once the rebuild is done, you can either use the "Unused Space" to create another Logical Drive (e.g. Logical Drive 3), or you can Extend Logical Drive 2 to utilize the extra space.
Once this is done, you'll see a larger block device available to your operating system.
- If this is Windows, the free space will be available and you'll need to extend it in the Disk Management console.
- If this is Linux, you'll need to make fdisk partition changes (or LVM craziness) in order to use the new space.
Also see: p212 Raid controller on SBS 2008 proliant g6