Here's Adobe's word on Clip Notes:
Getting fast, to-the-point feedback from clients is a crucial part of successful production, but it can also be a time-consuming chore. Adobe Clip Notes streamlines the process with an elegant solution based on two easy, accessible technologies: e-mail and Adobe PDF.
Export a video sequence as an Adobe PDF file with embedded or streamed video, and then e-mail the file to your reviewer. The reviewer plays the video with Adobe® Reader® and enters timecode-specific remarks into the comment box. After the reviewer e-mails back the comments and you open the file in Adobe Premiere® Pro CS4 software, the comments appear as clip markers at the appropriate timecode locations in the timeline.