Right now 10.6.2 is the safe choice. We already know what it takes to get it working, and everything does work. If you need to rely on your machine to get work done, you might stick with a tried and true version of the OS that we've all been running for a long time. You can pretty much know that 10.6.2 will be as solid as it ever was.
Long term 10.6.3 is the better choice. There are some significant changes and fixes to the OS, and many users have logged better benchmarks than 10.6.2. However, there are no new features, and most users will not notice any difference whatsoever.
If you do decide to update, make sure that you know that some of the best current solutions for some issues are to roll back kexts to previous versions. Caution! Doing this can destabilize the system and cause issues with applications. Or alternately, nothing will happen- and the kexts may turn out to be perfectly compatible. I've noticed no issues so far with mixing kext versions. But obviously this is an unsavory long-term solution.
Testing the update is strongly encouraged! A good way to do this is set up 2 drives or 2 partitions, and do 2 separate installs. One for 10.6.2 and one for 10.6.3. Any information that you can gather about your particular system and updating should be posted in the forum. It will help us come up with more vanilla solutions. Just make sure that you're using a fresh unmodified system as a basis for your testing.
For the very latest workarounds and solutions, check out the bottom part of the Mac OS X 10.6.3 Update post. Good luck!
PS: I haven't forgotten about the new guide! It should be out
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