I use an iPhoto album to keep track of my desktop pictures and have the desktop photo change every time I wake my PowerBook from sleep. After installing iPhoto 5.0.x, the feature of selecting an iPhoto album for use as a desktop picture source is not working very well at all for me.
I still want to use iPhoto to organize my desktop photos, but now I have to export them into a normal filesystem directory and use that in the 'Desktop & Screen Saver' System Preference panel, instead of an album in iPhoto. Every time I add/delete/edit a photo in the album, I have to re-export it.
So, I took a dive into AppleScript. I quickly found out that AppleScript cannot be used to directly export, but I didn't let that stop me. I have thus come up with an AppleScript that exports photos manually for a given album. The album and export directory are hard-coded in the script, but I have noted which lines of code need to be changed if you want to export a different album to a different directory.
Feel free to change the script to prompt the user for album to export and directory to which to export!
[robg adds: This is probably one of the most annoying bugs in iPhoto5, and it took me a while to figure out what was happening: you cannot set an iPhoto5 album to "Change picture every XX minutes" in the Desktop & Screensaver prefs panel. The option is simply grayed out when an iPhoto5 album is selected.
However, if you have albums created under previous versions of iPhoto, the Rotate option is still available, but it only somewhat works. Any images you add to that album in iPhoto5 are simply ignored by the Desktop panel.
So, in short, if you want to have an iPhoto5 album used for a set of rotating desktop images, you'll have to export them first. I hope Apple fixes this one quickly; duplicating hundreds of photos is clearly a waste of drive space and time!]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20050226135405959