There’s have been several published reports suggesting that Apple might use the Mac App Store as the main method to distribute Mac OS X Lion. What this would mean is that, upon ordering the upgrade, it would download to your Mac and show up in the Dock. To install, you’d just click on the Installer icon, and follow the usual steps from then and there.
All well and good. It would make it far easier for many Mac users to get ahold of their Lion upgrades without having to rush to an Apple Store or order a copy online. But you have to assume the upgrade will be several gigabytes in size, thus requiring a lengthy download. This can become particularly irksome if your Internet access is, shall we say, bandwidth challenged.
But the stories also suggest that Apple is not going to stop offering Lion on physical media. That would be no different from previous OS releases, and you can take your choice which method suits you best.
Of course, if you wanted a backup of a digital download, nothing would stop you from making a perfectly legal backup on a DVD, in case something went awry with your Mac’s hard drive. And don’t forget Time Machine and other methods of protecting yourself from lost data.