With Snow Leopard almost here -- and with upgrade pricing from Apple only US$29 for Leopard users -- many people are asking, "Why shouldn't I upgrade?"
Indeed, there's a lot to love about Snow Leopard. Though most of it is under the hood, it's there that all the goodness application developers can tap into lives. Snow Leopard will provide developers with new features and efficiencies to add to their apps to make us all even happier Mac users in the future, but we have to be running Snow Leopard in order to reap the rewards. Unfortunately, some of these changes also mean some of our existing applications and tools may not work, and we'll explain both why and what to look for as you make your way through the migration.
It Came Early
Apple had repeatedly cited September, 2009 as the timeframe by which Snow Leopard would be released. Obviously, they'll beat that target with the August 28, 2009 release date. Most developers, however, assumed Apple's estimates meant Snow Leopard would be released around the end of September, and many were caught off guard without having fully prepared any necessary updates. This means we need to be even more careful than we usually would.
One of the biggest features Apple has touted is Snow Leopard's 64-bit codebase. Our own John F. Braun has put together an article explaining what this means to you, so we won't rehash that here. What we will talk about, though, is what it means to your applications.
Device Drivers and Kernel Extensions - If you use any non-Apple hardware on your Mac, it's possible you've installed a custom driver to allow your Mac to properly communicate with the device. Previously, all of these drivers were compiled as 32-bit code. With Snow Leopard, they will eventually need to be 64-bit code. However, the first release of Snow Leopard will boot into 32-bit mode just like Leopard 10.5 before it, so most of these should continue to function just fine after the upgrade. Still, it's possible that other, hardware-related changes in Snow Leopard could render these unusable, so it's worth a trip to the manufacturer's Web site before upgrading to ensure you'll have success with all your devices.
Application Extensions or Enhancers - One of the greatest parts about several of Apple's built-in applications is their extensibility. That is, their ability to be modified or enhanced by 3rd party add-ons. Unfortunately, because most of Apple's built-in apps are compiled as 64-bit in Snow Leopard, all of these extensions need to be updated before they'll operate in the new operating system. Already there are reports of things like Mail Act-On and 1Password, two popular extensions for Mail and Safari, respectively, not working out of the box. The former is waiting on an update from the vendor, while a public beta of 1Password 3 is reported to work, but one must first do a "Get Info" on Safari and change it to run in 32-bit mode (which won't be a negative impact for most users).
Remember, too, that the Finder, Dock, and menu bar are all each separate apps that are updated as part of the Mac OS. Because of that, extensions like MenuMeters and iStatMenu also need to be updated to 64-bit in order to function at all under Snow Leopard. Thankfully the developers for both of them have indicated that updates are in-progress and will be released Real Soon Now (hopefully within two weeks).
Preference Panes - The System Preferences app, too, runs in 64-bit mode by default. However, it's been built to notice when you want to access a 32-bit-only Preference Pane and relaunch in 32-bit mode so all will work. Still, this can get a bit funky. Some panes, like TextExpander, have already been updated to fully function in 64-bit mode. Others will require the compatibility relaunch, and though this definitely works, we recommend keeping a keen eye out for an update to anything that you need which requires this.
Standalone Applications - For the most part, standalone applications will still continue to run just fine. They'll likely run 32-bit (unless the developer releases a 64-bit update), but for most of us that won't even be noticeable, let alone an issue. However, any apps that talk to hardware, burn DVDs, or perhaps use unpublished or otherwise unsupported hooks into Mac OS X may, indeed, no longer function properly. Again, it's worth checking the Web sites and support forums of your favorite software packages before you upgrade. Developers have had access to Snow Leopard builds for quite some time, so they should at least know the status of their app's functionality within, even if they're not yet ready with an update.
No More PowerPC Code
Snow Leopard is Intel only, meaning the operating system will not run on any PowerPC-based Mac. Additionally, Rosetta (the software which emulates PowerPC for those older, PowerPC apps we need to run on our Intel Macs) is not part of the base install of Snow Leopard, though it is an option. If you have any older, non-Intel apps you need to run, make sure you install Rosetta as an optional component during your upgrade.
Should I Upgrade?
This is definitely a "do as we say, not as we do," moment. At TMO, we'll all be upgrading on day one (and some of us have already!). That said, it never hurts to wait a few days to see what dust settles where. If you can't wait, though, we understand. We can't either! One thing that looks good is the Snow Leopard Compatibility Wiki. Check that for your must-have apps. If they're listed as compatible, you're good to go (but first prep yourself and your Mac with John Martellaro's excellent Snow Leopard Preparation guide). If not, wait until they are or find an alternative!