OS X Mountain Lion finally came down off the -- well, mountain! -- this week and leapt onto the Mac App Store, where it can now be purchased for a mere $19.99. But did you know that any Mac purchased since June 11, 2012 qualifies for a free update? Here's how to claim yours.

Apple has long made it worth buying a new Mac by offering eligible customers a free update to the next major version of Mac OS X, and this week's launch of OS X Mountain Lion is no exception.

Even though an update to OS X Mountain Lion is a mere $19.99 from the Mac App Store -- a drop in the bucket compared to previous full-version upgrades -- there's no reason why you should have to toss another 20 bucks in Apple's direction after spending a thousand bucks or more for the latest and greatest hardware.

That's where OS X Mountain Lion Up-to-Date Program comes into play. Qualifying new Macs purchased between June 11 and July 25, 2012 are eligible for a free update to OS X Mountain Lion, provided they submit their request by August 24, 2012; qualifying purchases made on or after July 26, 2012 will have 30 days from date of purchase to get theirs.

That means the clock is running for all of you 2012 MacBook Pro/Air buyers, but it also applies to anyone who's invested in an eligible Mac in recent weeks. The process is pretty painless, so here's what to expect.

Proof of Purchase

Before you begin, you'll want to prepare a proof of purchase document. This should be a scan or high-quality digital photo of your receipt or Apple online email confirmation in either JPEG, TIFF or PNG format that doesn't exceed 1MB in size.

In our case, we have an email confirmation from Apple.com, so no scanning or digital phone is required. We can either use the built-in screenshot feature of Mac OS X to capture it (Command-Shift-4, then hold down the Space bar to capture only that window) or simply use Print from the File menu of Mail.app, choose "Open PDF in Preview" and then Export the email in one of the three formats listed above.

Now you're ready to get started!

Purchase Details

While you have your email confirmation or receipt handy, take note of the date of purchase -- you'll need to enter it on the first page of the OS X Mountain Lion Up-to-Date Program application, "Enter your Purchase details."

For most of us, this one is easy: Enter the date of purchase, then use the Place Of Purchase pulldown menu to select where your new Mac was bought from. If this is an Apple store or Apple.com, you're done here; otherwise, you'll need to enter the Country, Reseller, City and State information as well.

Unless you're an Enterprise, Education Institution or Government customer, disregard the second option, "Right To Copy." This is only valid for those customers purchasing 20 or more qualifying systems with a Right To Copy license, and we're guessing that doesn't apply to our readers.

Be sure to check the "I accept the Terms and Conditions of the program" box, then click Continue.

Enter Your Details

Next, Apple needs your personal information in order to validate your Up-to-Date claim -- otherwise, they have no way of knowing if you're eligible to receive OS X Mountain Lion free of charge.

Required information here is your First and Last name (Middle name is optional) as well as an email address; you'll need to type this in twice to confirm it's accurate, as this is where Apple will send your Mac App Store redemption code.

Next, fill out your address and telephone number, and optionally your company or institution name, if applicable. Click Continue.

Enter Your Serial Number

Now you'll need to enter the serial number for all eligible new Macs. Choose the number of systems, which for most of us will be only one.

To find your serial number, go to Apple Menu > About This Mac and click More Info. OS X Lion users will find this number sandwiched between Graphics and Software; on Snow Leopard, it's under the Hardware Overview section near the bottom. Don't worry about accurately typing this information into Apple's web form -- you can double-click to select it right in the About This Mac window, then copy and paste.

Once pasted, be sure to select which kind of new Mac you're applying for from the pulldown menu at right. Then, you guessed it, click Continue.

Upload Your Proof of Purchase

Now it's time to send that proof of purchase file in digital form to Apple. Here you'll see confirmation of your qualifying Mac that says "Need further review" above.

If you have your proof of purchase ready to go, click the "+" button, select the file and click OK; once it's successfully uploaded, you'll see a small thumbnail version of the page appear in the grey area below. From here you can select and delete files or add as many as necessary for each Mac you'll applying for. Be sure to click Continue when you're finished.

Review Your Details

Now you're presented with a screen showing all of the details you've submitted. You'll want to make sure your name, address and email is correct, and there should be checkmarks next to "I accept the Terms and Conditions of the program" as well as "Receipts submitted." If everything checks out, click Confirm; otherwise, click Back to jump back and correct an entry.

Finally, you'll be presented with a green checkmark and the encouraging words, "Claim Submitted." You'll find a "claim reference number" at the bottom of this screen, which Apple tells you to keep a copy of for you records; this is not the Mac App Store redemption code, but rather a claim number the folks in Cupertino can use to identify you as a legitimate new Mac owner.

Redeem!

Now it's time to sit back and wait for an email to arrive at your inbox!

This will deliver your Mac App Store redemption code as a password-protected PDF file; simply copy and paste the redemption code into the Redeem section of the Mac App Store (found under the Quick Links section at right) and within moments, you'll be pushing OS X Mountain Lion onto your new Mac while keeping an extra 20 bucks safe and sound in your wallet.

Note: Given that OS X Mountain Lion has only just launched, you may get an Error 404 page after clicking the "Request your copy of Mountain Lion" button -- be patient and try again later!

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