"So does someone reading this Blog know what the big announcement is all about?"
Copernicus,
I don't know for sure, but I'm assuming that the announcement will be about Gulfstream's long-rumored “Global Express Killer.” The information I’ve come across on the internet over the last year or so is that Gulfstream will produce a clean-sheet 7,000 NM jet with a cabin significantly wider than present Gulfstreams (and wider than the GLEX).
Really letting my imagination run, I’d love to see them officially launch a supersonic airframe (maybe with SAI or Aerion).