Sure.
Final Cut Pro X's keyword feature allows you to keyword an entire clip or only a portion of a clip, and also you can have multiple keywords per clip. So far, this is also how it works in iMovie 9.x. However, in Final Cut Pro X, when you add a keyword, it will automatically creates a keyword collection in your event of all clips with that keyword. You can also create custom smart collections.
This can make it very efficient to do editing. For example, let's say I have shot 10 interviews, and I want to edit together several answers to Question 1, several answers to Question 2, etc. I would go through interview 1 and keyword each question, etc. Now, when I finish, I have a smart collection of all the responses to Question 1, etc, and I can easily choose the ones I want and add to the timeline.
Here are some good resources.
Moving Media http://youtu.be/fq4recVZjdI
Working with Libraries http://youtu.be/xQzYwrc1VWo
Understanding Libraries http://youtu.be/__wq1D9S-p0
Smarter Smart Collections http://youtu.be/gLPnK_vvk0w
Warp Speed Keywording http://youtu.be/azJ4J41JaZk
Batch Clip Renaming http://youtu.be/E1ql241Qytg
Light Speed organization http://youtu.be/Ilupsw68JPY
Smart Collections http://youtu.be/dYPxIqEPRnc