If you recently bought a new Mac that doesn't include OS X Mountain Lion, you can upgrade for free from the Mac App Store.
Customers who purchase a qualifying new Mac computer from the Apple Online Store, an Apple Retail Store, or an Apple Authorized Reseller - or an Apple Certified Refurbished computer from the Apple Online Store - between June 11, 2012, and July 25, 2012, that does not include OS X Mountain Lion can upgrade to OS X Mountain Lion for free.
If you fall into this category click here to apply for your free copy of OS X Mountain Lion. You have until August 24, 2012 to participate in the program.
Also, customers who purchase a Mac on or after July 26th that does not come with OS X Mountain Lion are eligible for the free update via this form. Those customers have 30 days to participate in the program.
None here as well. After several failed attempts to fill in the up-to-date program form, finally got through. Now no code for hours. Can't complain about a free upgrade though. Only want a confirmation it worked, I can wait all day for the download itself. It's not gonna escape from the Appstore...