Supports my point even more. The next "big" event to announce Vader is SDCC in July. No business is going to sit on a cash cow product like this for that long just to make a big entrance with it. Plus, if they announce this now, it'll be higher-profile because nothing else is really going on. Plus, I imagine there will be a lot of pre-orders as Christmas gifts (think the old Kenner Early Bird event from '77).
Seriously ask yourself if Sideshow needs an event like SDCC to promote the most awesome 1:6 Vader ever made?
I don't think so.