10.6.4 is now in the wild and available through SU as well as the Combo download, which is what I installed on my MBP.
...So far, also, no issues.
I've now completed the update to my Mac mini. Although I got it in early April, the 10.6.4 Mac mini-specific update (downloaded from the updates page) would not install. So for this install, I simply completed regular update by SU. All Ok so far, but I wonder about what qualifies for "Mid 2010" Mac mini update.
Edited by pbGuy (06/15/1007:01 PM) Edit Reason: Added Details
Originally Posted By: Apple Knowledge Base Article
You should back up your system before installation; you can use Time Machine.
Do not interrupt the installation process once you have started to update your system. You may experience unexpected results if you have third-party system software modiﬁcations installed, or if you've modiﬁed the operating system through other means.