Update: false alarm – B&H screwed up, error in their system – they do not have the camera in stock yet and they sent apolagizing emails to customers who ordered it (source).
Panasonic Lumix DMC-GH1 was in stock @ B&H earlier today.
Amazon has it in stock right now but for $2,499.99 (ouch!).
What that means is that shipments are already reaching store fronts.