Apple announced this afternoon at its quarterly earnings call that OS X 10.8 Mountain Lion will be released tomorrow. It’s a $20 upgrade and my MacBook Pro is among the supported models. This past week, I’ve been preparing my Mac for tomorrow’s launch.

First, I cleaned up my address book. This was more in preparation for my upgrade to an iPhone this fall than to Mountain Lion, however it was a productive activity to complete now anyway. I ensured that all my current mobile contacts are among my contacts on iCloud and deleted a bunch of contacts I’m never or have no intention of being in contact with.

Over the weekend, I spent a few hours cleaning up my applications and other data. I deleted several old games that haven’t worked since before Lion because they required Rosetta support for their Carbon underpinnings and several other apps that I never use or don’t want to license. Along the way, I discovered that Little Snitch has not been notifying me of updates because update checking wasn’t added until version 2.5—and of upcoming version 3 to which up might upgrade after its release. I also updated a bunch of apps that have sat untouched for a while since I use my Mac so much less than my iPad, especially when school’s not in session.

I also migrated my music from a separate partition on my hard disk to the same one containing OS X. For as long as I can remember since starting to use OS X over a decade ago, I have kept separate partitions on my hard disk for music, installers, and some other stored data. I can no longer remember why I once thought this was a beneficial practice. So, for Mountain Lion, I will be starting fresh on an erased, consolidated hard disk with only one partition.

After I download Mountain Lion tomorrow, I will clone my main partition (which now includes my music) and other stored data to my external drive, erase, install Mountain Lion, and restore my data. I expect it to be a several hour process and I’m looking forward to putting on music (with my iPad) and patiently working through it. I’m looking forward to exploring new features of OS X, including Notification Center and Mail VIPs.

I’ll be tweeting along the way with the hashtag #MLupgrade and my tweets will also appear on Facebook. I hope you’ll follow along.