...than a SEP question. You'll need to consider if you'll be using mirroring or clustering in SQL, and how the SEPMs will connect to the DB in either case.
As far as SQL clustering goes, all SEPMs would connect to the instance containing the SEP DB via the clustername. This instance would then move back and forth depending on which SQL Server is serving it at the time, and the SEPMs would follow (I think!).
SQL Mirroring would require you either do some DNS jiggerpokery to redirect the SEPMs, or run the SEPM Config Wizard to repoint the SEPMs, at the other SQL Server in the event of the primary one falling over.
I'd highly recommend you read up on the SQL side of things for a better understanding of it all.
On another note, is there any reason you don't want to setup SEP replication between the two sites, and just have Management Server Lists set so the SEP Clients will failover across the sites/SEPMs?