The other day someone on StackOverflow asked how to integrate jGrowl into a Chrome extension. They had a pretty good start, but missed some important details. I've uploaded a complete working Chrome extension with jGrowl to Github as part of my response to the question.
The question can be found here: http://stackoverflow.com/questions/15870797/jgrowl-issue-in-chrome-extension
The GitHub repository with the example implementation can be found here: https://github.com/stanlemon/jgrowl-chrome-ext