After a bit of a battle we managed to upgrade our environment to SCOM 2012, after letting everything settle we fired up the SP1 media and immediately had the following error.

Unable to Proceed
Setup could not detect the current database scenario.

Luckily for us after a bit of research, (Thanks to Stefan Roths’s blog for pointing us in the right direction) the resolution was quite simple, checking the registry HKLM\SOFTWARE\Microsoft\Microsoft Operations Manager\3.0\Setup
The following keys were empty DataWarehouseDBName and DataWareHouseDBServerName

After populating the relevant values for our DB server and Data Warehouse database the install allowed us to proceed.