A quick note that as of the posting date, there are a handful of plugins not yet available for the Creative Suite CS4 applications.
The list for me so far includes: all font activation plugins for Linotype’s Font Explorer X, “Select Menu” for Illustrator CS4, Canon’s Scangear CS plugin to access your scanner from within Photoshop’s Import menu, and plugins from developer Worker72a such as the ‘Zoom To Selection’ plugin for Illustrator.