It's looking pretty certain, based on the teaser Invite for Apple's October 20th Back To The Mac event, that Mac OSX 10.7 will be called Lion.
Perhaps that was virtually inevitable, given that Apple is running out of major big cat names.
OSX 10.0 was Cheetah, OS X 10.1 Puma, 10.2 Jaguar, 10.3 Panther, 10.4 Tiger, 10.5 Leopard, and OSX 10.6 - essentially a code-slimming and streamlined revision of 10.5 Leopard is Snow Leopard (although in nature the Snow Leopard is actually a completely different species from the Leopard).
There are actually a fair number of cat names still unused by Apple, although most are so obscure that they wouldn't be suitable for an operating system trade name. According to
one wild cat species resource site, there are 36 distinct species of non-domestic cat.
One appropriate name still available is Cougar, although it's a synonym for Puma (not to mention the link with sexually predatory middle-aged women), already taken for OS 10.1, but then likewise Panther, at least in its North American vernacular context. The largest North American wild cat species is regionally known as Cougar, Puma, Mountain Lion, Panther, Painter, and Catamount.
Other potential candidates include Ocelot, Lynx (already used in a software context for a text-based Web browser), Bobcat, and Wildcat - the latter a name used by Grumman for a World War II era naval fighter aircraft.
However Lion was probably the most logical choice for OS 10.7, but what will OSX 10.8 be called?
Incidentally, the original OSX had a bear code name - "Kodiak", so switching to another animal family for naming future OSX versions would not be without precedent .
OSX 10.8 Grizzly, anyone? Panda? Koala? (Put the crayon down... we know it's not a bear!).