How do I install Mavericks now that Yosemite has been released? I have a late 2009 iMac running Mountain Lion, I also have a Macbook Pro running Mavericks. I have been planning on installing Mavericks on the iMac, but now that Yosemite has been released, Mavericks is no longer available on the Mac App store. 

How can I install Mavericks on the iMac? As you can guess, I'm not an early-adoptor, so not interested in installing Yosemite for now.

Even though I have a Macbook Pro with Mavericks, it came installed with Mavericks, so it is not in my Mac App store 'Purchases', but 'Mountain Lion' is.
Take it to the Genius Bar. They have installers for every OS.