It seems that the OS X 10.5.7 update causes issues with Adobe's CS4 applications and OS X's Spaces feature. As noted in this Apple Discussions thread, clicking an icon in the Dock for a CS4 app that's in a different Space won't cause that Space to become active.
Adobe's Photoshop CS4 Read Me clearly states that Spaces isn't a supported feature:
Spaces (Macintosh only)The truth is that Adobe made some hacks to the window model on OS X to be able to put flash panels on its CS4 apps. This is really annoying, as it totally broke my workflow; I wish there is some way to fix it. I have a workaround for this -- it's annoying, but it works. After you press Command-Tab to activate Photoshop, press Control-Tab to switch to another Photoshop document, and it will take you to the correct space.
We do not officially support the Apple OS X Leopard "Spaces" feature. If you are experiencing problems when using Photoshop CS4 and Spaces, please contact Apple Support.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20090518120827503