Internal drive on MacBook won't appear on desktop Why doesn't internal drive appear on desktop after a fresh install of Snow Leopard 10.6.8?
Since Snow Leopard the hard drives aren't shown on the Desktop by default. However if you upgraded from Leopard or earlier it does honor the original settings. However, some updates will disable this setting during the upgrade. 

Have a look under Finder preferences and make sure the Hard Disk box is ticked.