Initially, I was unable to get iAuto to install without errors. Being low on time, I let the client submit a trouble ticket to iAuto, and I was told there were issues with the .htaccess files and permissions (although, the client couldn't offer specifics).
I was able to get the 3.2 upgrade to install today, after uploading the files via Slackware as opposed to Windows. I don't really see what could be the root-cause, other than maybe the Windows FTP client wasn't setting permissions.
My biggest problem with installation was the fact that my host doesn't offer access to tar. It would be nice to be able to upload just the tar file, make a php script (exec('tar xvf iAuto.tar'); exec('chmod a+w filea fileb ...')

, and then just run the install.php. The reason it would be nice is because the host ftp likes to time-out while uploading the 1300 or so files iAuto contains. On my first install attempt after the initial upload, I noticed that a lot of files weren't transferred (probably on the files that were being transferred at time-out). This caused install errors, and threw me off for a good 30 minutes.
I didn't notice any way to upgrade the site, so I ended up re-installing the site w/the new 3.2 files. This has caused me quite a headace, after realizing the the static pages are nowhere to be found in the 3.1.2 site backup (FTP xfer to my Desktop). I was going to have the client backup the database, but he was having trouble with his host's cpanel and I told him to just blow it out. I only expected to lose trivial template DB items, not the static pages.
As for the iAuto manual, I had a hard time reading through it. I browsed through the content, somewhat, but my impression is that it could be much more thorough. Just as an example, the static pages section only briefly describes the static pages. It doesn't tell you that if you blow out your development DB without backing it up, you lose your static pages too.
