The Host can make anyone in the meeting a Presenter, as long as that Guest has GP4 or they have joined the meeting using a Java enabled web browser running Java 1.3 or higher.
Guests can test their computer for Java using the Browser Compatibility Test link on the Join page or by going to:
http://www.gatherplace.com/testTo make a guest the presenter, simply click on their name in the participant list and choose 'Make (Guest Name) the Presenter'.
Note: The Advanced Features are selected by default for guests joining the meeting.