As Internet search assistance for library patrons, this is tempting. The librarian could demo some searches in the real time mode, and students could leave search results and ratings for the librarian to review. For online courses, a group could use it for research on a group project.
Of course, in order to do this all participants need to have IE7, a Windows Live account, and install a plug in to IE. I'd be tempted to try it out as search assistance, but one of my rules is to only require accounts and downloads when it is absolutely necessary. There are other services that allow someone else to follow my web browser without an account, mostly video conferencing systems. I've tried Vyew most recently. A little slow and the connection was fussy, but overall it worked.
Right now, this system is very experimental and it only works in the major search engines. However, I suspect (and so do others) that similar systems will eventually become common.