“Since OS X Mountain Lion will be distributed over the Mac App Store, the easiest method of upgrading is installing it over your current OS. Upgrading over the current OS will keep all of your files, settings, and applications in place,” Brian writes. “The other method (clean installing), however, will erase your entire hard drive and give you a fresh copy of OS X Mountain Lion.”
Read more in the full article here.
[Thanks to MacDailyNews Reader "Fred Mertz" for the heads up.]