In addition to changing the organizational structure for databases, Exchange 2010 has improved the physical types of storage you can use with solid performance returns. For example, Exchange 2010 supports SATA disk drives and RAID-less configurations. You can go with a SAN, DAS (direct-attached storage), or JBOD (just a bunch of disks) storage and get reliable, decent performance. (Note: Microsoft only recommends JBOD for very specific configurations, for example, an HA configuration where at least three mailbox database copies are used.) Microsoft claims that Exchange 2010 has half the disk IO compared to Exchange 2007; if true, this means you can use lower-performance disks than before and still get enterprise-class results.
But let me drop the next informational bomb on all of you folks who did your best to learn the high-availability options for Exchange 2007: Local Continuous Replication (LCR), Cluster Continuous Replication (CCR), and Standby Continuous Replication (SCR) are all gone in Exchange 2010. Well, in the case of CCR and SCR they aren't quite gone, but they've morphed into something new. Elements from CCR and SCR have been combined into the new HA framework.
To start with, Single Copy Clusters, which was a carry-over from legacy Exchange clustering using shared storage arrays, are gone. The three remaining high-availability methods (LCR, CCR, and SCR) had been used to provide disk, server, and site resiliency, respectively. Of those three, LCR (which allowed you to make a database copy on the same server in Exchange 2007, is eliminated) In Exchange 2010, they have become part of something called Database Availability Groups (DAGs).
DAGs provide automatic recovery by using small portions of Windows Failover Clustering and a new internal component of Exchange 2010 called Active Manager.using continuous replication. That's a real change from Exchange 2007, whose only automatic recovery capabilities were those using failover clustering services. LCR and SCR did not, so you manually had to provide the swap over to the passive data in those cases. CCR used failover clustering and was automatic.