This week's Mac OS X 10.5.2 update is in total the largest I can remember at nearly 400M.

I say "in total" as it seems to me that splitting the display update into a separate package was artificial, unless it turns out that it is only needed for certain hardware. (Apple's notes say it is recommended for all users.)

Exactly which of the fixes in 10.5.2 are most important depends mainly on which of the issues have been causing problems for you.

Travel plans mean I'm writing this ahead of time, and consequently I haven't had an opportunity to install 10.5.2 yet. I'm glad to see an opaque menu bar is now officially supported, and I'm confident that the new Stacks views will suit me, as I made extensive use of dropping folders into Leopard's Dock. The provision of a menu bar item for controlling Time Machine makes sense too.

As far as I can see, the bug preventing Secure Empty Trash from completing properly in some circumstances hasn't been fixed, and that's a disappointment.

I've heard plenty of complaints about AirPort connection reliability and stability under Leopard, so let's hope Apple's fixes do the job from those suffering from Wi-Fi problems.

There's a bunch of bug fixes for the Finder, iCal, iChat, Mail, Preview, Safari and other components, but I can't say I've encountered any of the problems Apple describes.

Although it doesn't affect me directly, I'm pleased to see new iSync support for a couple of Samsung phones - it shows iSync is still alive within Apple, and the list of supported devices hasn't been frozen.

And 10.5.2 also includes some security updates, including some that overcome flaws that could be exploited to run arbitrary code. One such bug was in X11, and was fixed on October 2, 2007 by the X.Org Foundation. Even though that was a few weeks before Leopard shipped, it was obviously too late for inclusion in 10.5, but you have to ask why it didn't make it into 10.5.1.

A corresponding updater has been released for Mac OS X 10.5 server, and for developers there's a new version of WebObjects.

If you're still on Mac OS X 10.4.11, don't overlook Security Update 2008-001, which came out alongside 10.5.2. This includes the relevant security fixes from 10.5.2, plus other patches specific to 10.4 - including one for a vulnerability disclosed as part of the Month of Apple Bugs back in January 2007. That's not what I call a timely response. Even though a local privilege escalation vulnerability is arguably less serious (to most owners) than a remotely exploitable flaw, it seems strange that it took Apple a year to come up with a fix.