Following up on the 10.5.6 upgrade: The most common issue people seemed to have upgrading to Leopard 10.5.6 was that the install would get stuck at 'configuring installation'. It happened to me, and judging by the Apple support boards and others, it was a pretty widespread bug. We reported the problem Tuesday.
Apple has now responded and acknowledged the issue with a support note. It says that the problem can be caused by getting an update that "was only partially downloaded". Of course, what was not explained was how Apple provided only a partial update, and why and how this got past Apple QA?
For most people, installing the combo update solves the install freeze. Apple is recommending that people use Software Update, so most likely the bad package has been removed from the servers. There are still some nagging issues with Mail, mounting network volumes, Safari, and the other all too usual issues following an OS update.
Of course, for many, the update went just fine.
Thanks to all who wrote in and shared their experiences.