Here's just a quick write-up of my first impressions and findings in OS X 10.8 Mountain Lion GM Build 12A269. Hardware: MacBook Pro with Retina Display 2.6 Ghz i7 / 16GB RAM / 512GB SSD Resolution Setting: Best for Retina 1. The installer doesn't say "Upgrade" anywhere, and just says "install", but it does an upgrade. Took about 20 minutes. 2. To drag items from the dock, you have to hold them out of the dock about a second longer until the little *poof* cloud appears. 3. /private/var/logs/kernel.log is nowhere to be found. 4. The first time I went to the "Mail, Contacts & Calendars" System Preference, all of the Chinese oriented sites where listed. Now they are gone, but of course there are the additions of Twitter, vimeo, and flickr. 5. I added my twitter account, it displayed an error saying the account was already added. It didn't show the account in the list until I logged out and back in. 6. First time I opened Pages.app, I was prompted for permission to give it access to my address book. 7. I'm noticing the display stutter more than before in some areas, less in others. Maybe the new system needs to build up it's cache before things get better? 8. Dictation is awesome 9. I wish dictation automatically inserted commas, periods, and exclamation points. 10. The Display system preference has three choices for resolution when you're using airplay. The first is "best for retina display", the second is "best for airplay" and the third is "scaled" which gives you choices of resolution. 11. Despite reports to the contrary, both Pages '09 and Parallels 7 run fine. 12. iCloud tabs doesn't seem all that useful until iOS 6 is released 13. I wish I could change the dictionary "Look up" from "Tap with three fingers" to the classic "Tap with three fingers twice". I have to disable it because I would rather use MiddleClick to have a three finger tap work as a middle click for opening web pages in a new tab. 14. Just found a new option in General Preferences "Close windows when quitting an application". Yes! Having open windows restored when I start an application really annoyed me. After using an app for a while, the windows get messy and when I start the application back up, I want a clean-slate to start with. 15. Screen Saver Preferences looks cleaner and now has icons for each screensaver/slideshow 16. "Show all tabs" button in Safari looks very nice! It's kind of like the iPhone tab switching. Shortcut key is Shift-Command-\ As I find more interesting things, I'll try to add them to this post. I can answer questions too.