Hi,
The KB2425714 is explaining how to install your Operations Manager databases and reporting on SQL 2008 R2.
Notes from the Operations Manager Team Blog:
Support is divided into two phases.
Phase 1: Clean install of OM2007R2 on SQL 2008 R2.
Take a look at the KB to get OM2007R2 installed on a SQL 2008 R2 database server. In order to get the OM databases installed we had to go a different route from what's in the deployment guide so take a look at the KB.
Phase 2: Support upgrading SQL to SQL 2008 R2 with OM2007R2 already deployed.
Supporting this scenario will be coming as part of a future CU for R2. Stay tuned!