Phil Jackson will be there for sure, since his Lakers will be in town for the..actual game. Plus John Paxson will most likely be there as well as well as Bill Wennington (current radio broadcaster).
But other Pip teammates I've heard may attend: Michael Jordan, Dennis Rodman, Horace Grant, Stacey King, Will Perdue. We shall see. The Bulls list only Jordan as a confirmed attendee, as far as I know.
Go to Bulls.com for all sorts of Pippen retrospectives. And here's a post I did in September (when this ceremony was first announced) regarding other numbers the Bulls could retire. And lastly, my sappy Pippen retirement post from October, 2004.
Obviously I'm not one to constantly pine for Dynasty nostalgia, but this should be a fun thing to watch.