Storage vMotion in 5.0 does IO Mirroring
Migration is almost 2x faster than 4.1

Empty disk is created on target vmfs, IO is written to both disks, and mirroring is started to move disk
Pause and resume time for VM moving over storage vMotion is now controlled and never more than 2 seconds

Snapshots
Preserve the state of a VM
config state
memory state
disk state

Components:
Snapshot descriptor file *.vmsd
Snapshot config file *.vmsn
snapshot delta disk *-delta.vmdk

Snapshot File Placement:
Descriptor and config file in VM home or SnapshotDirectory
Delta disk in same location as the parent disk

vSphere 5.0 supports storage vMotion for linked VMs

RoadMap:
Simultaneous vMotion and Storage vMotion
Inter-vDS vMotion and Storage vMotion
Inter-vCenter vMotion and storage vMotion
vMotion and Storage vMotion across geographies