Unfortunately, I've recently had reason to want to check the SMART status of my PowerBook's internal disk. Apple's Disk Utility will tell you a simple pass/fail summary of the SMART status of the disk, but it won't go into any detail, show you logs, or details of particular errors. What's more, I believe that it only looks at certain classes of errors to determing the Verified of Failing status, and so if the drive is experiencing errors, such as its firmware silently remapping sectors, it's still shown as A-OK.
I decided to go hunting for some more useful utilities, and first discovered SMARTReporter which displays an icon in the menu bar showing you a visual status of the disk. This utility, however, appears to use the same criteria as Disk Utility for determining as simple pass/fail status, so in this particular case isn't that useful to me. It is handy in a more general sense as it can monitor multiple disks, and upon a SMART failure it can do any combination of: pop up an alert dialog, execute another program or send emails to multiple addresses.
So, digging a bit deeper, I then found the smartmontools, which consist of smartctl and smartd that together will report on a whole lot of low-level SMART information, including showing the drive's error log, and other useful information. smartmontools run at the command line only, so you do have to delve into Terminal to get at it, but they provide a wealth of information that is difficult, or impossible, to get in any other way. I've got more information on them available in a recent blog posting.
What I'm going to do now is, through a bit of magic with dd and DiskWarrior, to add a line to the daily cron script to check the SMART status of my internal hard disk, and let me know if there are any errors at all, not just something that DiskUtility thinks is worthy.
[robg adds: I downloaded and installed the package (following the "install from source" instructions, and it worked as described -- ./configure, make, and sudo make install installed the package. It seems to work with the SATA drives in the Dual G5, even though the site doesn't make it clear that it will do so.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20060516171818393