S.M.A.R.T. support shouldn't be related to the number of partitions or the filesystems used on them, as S.M.A.R.T. is a feature of the actual HD/SSD.
But there appears to be a number of scenarios when access to this information may not be available:
Depending on the type of interface being used, some S.M.A.R.T.-enabled motherboards and related software may not communicate with certain S.M.A.R.T.-capable drives. For example, few external drives connected via USB and Firewire correctly send S.M.A.R.T. data over those interfaces. With so many ways to connect a hard drive (SCSI, Fibre Channel, ATA, SATA, SAS, SSA, and so on), it is difficult to predict whether S.M.A.R.T. reports will function correctly in a given system.
Even with a hard drive and interface that implements the specification, the computer's operating system may not see the S.M.A.R.T. information because the drive and interface are encapsulated in a lower layer. For example, they may be part of a RAID subsystem in which the RAID controller sees the S.M.A.R.T.-capable drive, but the main computer sees only a logical volume generated by the RAID controller.
http://en.wikipedia.org/wiki/S.M.A.R.T.#Visibility_to_host_systems
