A couple reasons. First, its new release season. Automakers are currently trumpeting the new cars that are going on sale right now. GM is more concerned with hyping the G6, Cobalt, and other October releases than using up space in the press to showcase a vehicle that is many months from showrooms.
Second, we are on the verge of auto show season. By this point, any new news on upcoming vehicles is being withheld for announcement close to or at the auto shows where they can generate a lot of hype with the press and public, and not take away from hype regarding their current intros.
Finally, I think the Solstice has been a rather unusual vehicle development and production program, as far as public knowledge about it is concerned. Not only has it been a confirmed project for over a year and a half, we have seen the production example for that long. Most companies would not show it off with so much lead time, as development work continued. Then to have hand built test mules driven and reviewed by the press more than a year before pre-production cars will even role out of the factory is almost unheard of. Ford didn’t invite people to test the Mustang development a year ago and write it up for all to see. Corvette test mules were not in magazines a year ago. Heck, we didn’t know what it was officially going to look like a year ago, much less a year and a half.
No, the Solstice has been a somewhat unique concept to production vehicle. Maybe there just isn’t that much more info to give on it either, except final specs and details on options, colors, the top, etc.