During the deployment of System Center Operations Manager 2007 we realized that the database is not supported on Itanium (IA64) hardware. This was a big issue for us, because we only had IA64 hardware for our database machines. So a sick idea came to our minds: just install it on a temporary x86 or x64 machine - with the exact same machine name as the final IA64 production machine, detach the database and move it to the IA64 and re-attach it there.

After that, you have to ensure that the broker function is enabled on the DB. To do so, execute the following query in the SQL management studio (assuming you named the database 'OperationsManager':
SELECT is_broker_enabled FROM sys.databases WHERE name='OperationsManager'

This should return '1'. If not fire up the following statement (again, assuming the database is named 'OperationsManager':
ALTER DATABASE OperationsManager SET ENABLE_BROKER 

If the service broker is not enabled you might get errors or hangs during discoveries and submitting tasks. 

So far this is working great for us, it's still not clear if a setup like this is supported by Microsoft. But there really should be no difference running the DB on a IA64 instead of running it on a x64. No binaries are installed by the setup, only the database schema is created. As far as I know, Microsoft is working on IA64 support for the database - maybe a Service Pack 1 thing...

Update:

You also have to be sure that the CLR (.NET Common Language Runtime) for stored procedures is enabled. To do so:
EXEC sp_configure 'clr enabled', 1;
RECONFIGURE WITH OVERRIDE;
GO