We are on the eve of the WWDC, and during the conference there will undoubtedly be software updates available for a variety of Apple products, the most expected of which is the upcoming 10.6.4 update that may include Safari 5. The update has been under development for a while now, and while we cannot be certain of exactly when it will arrive, folks are speculating that its release is near.
As with any OS update, there will be a number of changes to core technologies, drivers, and included applications that will benefit the vast majority of users, but also may result in problems for a few users' configurations (i.e., a common one in the past being printers and scanners not working).
Since these updates have been tested by Apple on all supported hardware, especially with fresh system software installations, you should be able to reduce the possibility of errors by installing over as clean and as healthy of a current installation as possible. In addition, you can take some steps to ensure your data is safe and the computer is ready for the update. We outlined these steps in a previous article for the last update to Snow Leopard, which will also apply to the current and future updates.
(originally written for the 10.6.3 update)
Be sure to read through the article and consider the various installation options that will be available for the update, as well as the preparation steps. These steps can be done at any time and multiple times, but preferably done right before applying the update.
If you are wondering whether or not to upgrade, you might consider waiting a few days or weeks to see if any major problems appear. While full incompatibilities with system updates are relatively rare, Apple cannot guarantee third-party applications or devices will work with the new system software, so before updating be sure to check the with the developers of any software you use and need, to see if there are known issues with the latest OS update.
Additionally (and though even more rarely), an update may have a few undiscovered bugs that can affect some systems, so be sure to check the Apple discussion boards and other sources like MacFixIt to ensure no problems exist with your setup before installing the update.
Despite the potential for problems, if you have a full backup of your system, you can always try the update, and revert if any errors do occur. We will keep our eyes out for any issues, and report them if they appear, but fully expect for the update to be smooth and beneficial for most users.