O rly, is that the distinction? I actually thought this happened with Lion.
If that is the case, carry on Apple. Upgrade your machines people, anyone can save up for something better over 6 years. Your current jalopies will probably net a couple hundred on the second-hand market as well.
I figure if you own a MacBook 5,1 released in Fall 08, and this is the last OS it can take, you should be up to date till Summer 13, and if you had saved 92¢ per day you would have enough to buy a brand new top-end MacBook* then. Seriously, less than a cup of coffee.
*the line no longer exists, but you can get a comparable Air for about the same.