Apple has put OS X Snow Leopard back on sale at its online store, at a cost of $20, notes French site MacGeneration. The software was originally pulled around the time of Mountain Lion's release. Snow Leopard is now two generations old, making the software's return somewhat unusual.
It serves as an important bridge for Apple, however, since the OS is the oldest one with access to the Mac App Store, and hence the ability to upgrade to Mountain Lion. Combined with it being the last version of OS X released on disc, the software can be essential for people with older Macs nevertheless wanting to stay current with apps and features.