I've had a few days to cull through all the info on Mac OS X 10.8 ("Mountain Lion") and play around with the Messages beta. Here are some preliminary thoughts.

AirPlay Mirroring

One of the features of Mountain Lion I'm really looking forward to is AirPlay Mirroring, which lets you stream what’s on your Mac to your HDTV via an Apple TV.

Right now the only product I know of that can do this is the MacTivia (see our review at http://macte.ch/ksZpI). And as far as I know, this is the first time the concept of streaming computer content has been built right into an operating system.

Being able to view my Mac's content on my HDTV will be very convenient. Heck, I've ripped many of my DVDs to my Mac's hard drive. Now I can play them on my Mac and view them on my large screen TV.

AirPlay Mirroring on the Mac may be bad news for the makers of the MacTivia. However, it could help spur sales of the Apple TV.

Messages

Overall, the beta of Messages -- the replacement for iChat -- works pretty well. It does everything iChat does and more. For example, it comes with the Mac version of the iMessage app on iOS. You can send unlimited messages to anyone on a Mac or an iPhone, iPad, or iPod touch running iOS 5. What's more, you can start a conversation on your Mac and pick it up on your iPhone, iPad, or iPod touch. Pretty cool.

You can send photos, videos, documents, contacts, messages and attachments to an individual or a group. With Messages, you can see when your message has been delivered and when someone’s typing a reply. Turn on read receipts, and they’ll see when you’ve read a message. With end-to-end encryption, your messages stay safe and private. Also cool: you can switch to FaceTime directly from Messages.

However, let me get to one of my biggest grips about Apple's ID procedure. It makes absolutely no sense that the company can't find a good, streamlined way for a user to meld different accounts with different IDs (the iTunes Store, MobileMe and iCloud, for instance) into one across-the-board ID.

Gatekeeper

I'm not sure whether developers will love or hate Gatekeeper, the new security measure in Mountain Lion. I suspect it will be a bit of both. Apple says -- surprise! -- the safest place to find apps for your Mac is the Mac App Store. That’s because the developers who create them are known to Apple, and the apps are carefully reviewed before they’re accepted in the store.

The company says the goal of Gatekeeper is to help you avoid malware even when you download applications from places other than the Mac App Store. Hence as part of Gatekeeper, Apple created the Developer ID. Part of the Mac Developer Program, Apple gives developers a unique Developer ID for signing their apps. A developer’s digital signature allows Gatekeeper to verify that their app isn't known malware and that it hasn’t been tampered with. If an app doesn’t have a Developer ID associated with it, Gatekeeper can let you know before you install it. I

According to Apple, a digital signature makes it possible to verify that an application comes from a developer with a valid Developer ID and that the application hasn’t been tampered with. Digital signatures are created by combining a secret key known only to the developer with a digital summary of the contents of the application. It’s all wrapped together in an encrypted file that becomes part of the app. Gatekeeper checks the encrypted file to make sure everything is OK.

For maximum security, you can install and run only apps from the Mac App Store. You can choose to install and run apps from the Mac App Store and apps that have a Developer ID. Or you can install all apps from anywhere, just as you can today. You can even temporarily override your setting by control-clicking, and install any app at any time. Gatekeeper leaves it all up to you.

There will be three options: allow apps from anywhere (which is how Mac OS X currently works), allow only Mac App Store apps, allows Mac App Store apps and identified developers. But here's the semi-controversial part: the final option is the default one. In other words, you won’t be able to install any app from the web on your machine unless you change the default -- something Mac newbies may not know how to do.

iCloud

John Gruber of "Daring Fireball" (http://daringfireball.net/2012/02/mountain_lion): says that Mountain Lion's iCloud document storage (and Mountain Lion REALLY wants you to use iCloud) is biggest change to Open and Save dialog boxes in the 28-year history of the Mac. Mac App Store apps effectively have two modes for opening/saving documents: iCloud or the traditional local hierarchical file system."

I'm glad that Apple isn't forcing us into an iCloud only mode. Cloud storage is well and good; however, I suspect there are still lots of folks like me who are going to want their own personal, on-premise back-up copies of their files.

Miscellaneous

Why no mention of Siri, Apple's voice recognition, for Siri? Is it now coming to the Mac? Or is Apple simply holding back some info on some of Mountain Lion's features for now? I think -- and hope -- it's the latter.

However, "Wired" thinks there are several logistical challenges to bringing Sir to th Mac. You can read about it at http://www.cnn.com/2012/02/20/tech/innovation/apple-siri-osx-mountain-li... .

With Mountain Lion, Twitter sharing will come to the Mac, too. But what about Facebook? Integrating the world's largest social network seems like a natural step.

Apple has told "Pocket-lint" (http://www.pocket-lint.com/) that OS X 10.8 Mountain Lion will be exclusive to the Mac App Store when it arrives. according to Pocket-lint. I can understand that (well, sorta) but I still think it needs to be available on a flash drive as Lion is.

What will Mountain Lion cost? Apple hasn't said, but I'll be amazed if it's not US$29.99. That's what Apple has charged for Snow Leopard and Lion.

-- Dennis Sellers