In their E3-Report Just Adventure + claims to have wiggled some info out of LEC. According to JA+;
LucasArts has not one but two adventure games in development. The LucasArts rep was very cagey about these two games; he did say that one will be a sequel (but he didn't say to what; our loud speculating was met with an utter and complete poker face) and the other will be completely new. He assured us that LucasArts has absolutely no intention of ever (then qualified that to "in the foreseeable future") abandoning the adventure genre.Also, they got Grog.
Keep in mind that this is not official as the E3 mojo-monkeys badgered everyone they met including Simon Jeffery and Mike Stemmle and Sean Clark. Repeat, not official!
Source: Just Adventure