Some of the details for SQL Server 2012 are out now, and as expected, we have feature limitations in various editions. I was hoping for a change, and maybe it will come at some point in the future. I did expect there to be scale limitations and there are. As noted here, the Standard edition is limited to 64GB of RAM. It wasn’t too long ago that I would have considered that high a RAM limit to mean I’d never need Enterprise Edition, but these days I am finding more and more database servers with 32GB, 64GB, and more RAM inside them.
The post notes that the buffer pool will not grow beyond 64GB, though it doesn’t mention limits in any of the other memory spaces that SQL Server uses. However assuming that the memory outside of the buffer pools scales, it might be time to think about installing extra instances of SQL Server on a single host if you are licensing by the core. With a commodity server costing under $10k with 6 cores and 96GB of RAM (no HDDs), one could easily consider placing 2-3 SQL Server instances on this hardware with each getting 24+GB of RAM.
I think that virtualization is the best way to share physical resources, but the changing licenses for SQL Server 2012 might have a few of us rethinking that, especially as we consolidate legacy systems that might happily co-exist on a larger physical server, with smaller data sets, lower hardware requirements, and a cheaper edition of SQL Server.