How do I refresh a "Lion" iMac to run "Mountain Lion" (factory install, wipe drive) What is the easiest way to upgrade a 2011 iMac to Mountain Lion, including a full drive reformat? 

I also have a new MacBook which was purchased with Mountain Lion. Do I still need to buy Mountain Lion for the iMac?

Booting with Cmd-R will allow a
http://support.apple.com/kb/HT4718

Here are some ideas:


Buy Mountain Lion in app store, then upgrade, then boot with Cmd-R to reset the drive.
Like #1, but first do the Cmd-R to reset the system, and then buy Mountain Lion in app store to upgrade.
Create install DVDs from Macbook Pro with Mountain Lion (how?) although I'd to use another machine to burn the DVDs. Or maybe use an external USB hard drive?


Update: I found this program http://liondiskmaker.com/
And this which suggests how to get the image on a new mac that has mountain lion http://hints.macworld.com/article.php?story=20110831105634716

Thanks,

Justin
I always do option 3. You should be able to pretty much follow these directions, even though they reference Lion: http://forums.macrumors.com/showthread.php?t=1189888

Long story short: When you buy an app from the app store it is stored on your drive in a format that can be burnt.

Of course, the USB drive option is also doable and it sounds like that would be easier for you.