JMS has posted his schedule for Saturday July 14 along with these tantalizing hints:

My Saturday schedule at San Diego Comic Con: 11:15 DC graphic novel panel; 12:45 Before Watchmen; 2:00 spotlight; 3:30 signing. If all goes as planned, expect some really massive news at the spotlight. (Not necessarily B5 related.)

Of all the spotlights I've done, this may be the single most important...something I've been working toward for over a year now. For the folks attending SDCC, spread the word, because this is one you're NOT going to want to miss.