now THIS should make for a very interesting conference!Apple, Inc., CEO Steve Jobs and Microsoft Corp. Chairman Bill Gates, the seminal figures in the development of the personal computer, will make a rare joint appearance at The Wall Street Journal's "D: All Things Digital" conference this year. The two men will jointly discuss the history and future of the digital revolution in an unrehearsed, unscripted, onstage conversation on May 30 with D co-producers Walt Mossberg and Kara Swisher.