According to James Hibberd at The Live Feed, HBO’s Game of Thrones is “not expected” to have a presence at this summer’s San Diego Comic-Con, which falls in line with what we’ve heard over here at Westeros.org. This seems to be supported by the lack of reference to the series among the announced panels from HBO (who are certainly featuring True Blood). It also makes some sense, due to the fact that it’s almost a year before the show premieres, and the filming starts very close to the time of the convention—not an ideal time to drag cast and crew from Northern Ireland and North Africa for a whirlwind press junket.
That said, the possibility that teasers or promotional posters might first see the light of day at San Diego Comic-Con certainly exists. If you’re attending the convention next month, we’d certainly suggest visits to HBO’s booth (they’re almost certainly exhibiting), asking some questions, and expressing your enthusiasm for the show.
UPDATE: Maureen Ryan also confirms that HBO’s not holding a panel for the series, given the logistics of having production starting in Northern Ireland at the same time.