Following a link on Slashdot, I came accross this (simplified!) history of UNIX. The time line includes all major variants and can be downloaded as a PDF that prints on 17 sides of A4. The interesting thing on this graph is that the number of different variants seems to be going down rather than up. Could it mean that some expensive proprietary variants are being phased out in favour of Linux? As if further proof was needed, Solaris has been moving towards Linux compatibility for some time and IBM has been seriously pushing Linux, to the point where it is now easier to find references to Linux than AIX on their own site and they are spending millions on it! Even Apple's Mac OS X is now a variant of UNIX. The battle against Windows is only just beginning.