Tendo City

The Zelda crossbow game sounds interesting. Resident Evil: Umbrella Chronicles ... we'll see, perhaps.
Ghost Squad ? That's the most traditional lightgun game of the three, being a straight arcade port, but sure... I actually played Ghost Squad in a the arcade once. It's okay... nothing really special, but a decent lightgun shooting game.

What I really want, though, is Terminator 2: The Arcade Game (SNES) in Wii VC with backwards compatibility support. And Duck Hunt. :D

The Zapper is made out of 100% Nintendo, they'll definitely bring out a new IP for it. The fates of HAMMER and Disaster are in strange floatiness which doesn't really make since because they were basically finished games... possibly turned in to lightgun games. But I dunno, I have a feeling the new IP will be a zoo-prize to everyone. I doubt Nintendo's lightgun IP will use real guns... remembr Battle Clash?

Well, the Zapper is coming with the 'Link's Crossbow Challenge' game, as detailed in that first link. I don't know if Nintendo would do one with realistic, modern-day guns... it does seem like it'd definitely be out of character. Battle Clash 3 might fit, though. :)

Here's what I don't get. Is this Zapper thing really even needed? It seems to me like it's just a plastic shell you wrap around a Wii controller, but I've been fine just using the controller normally.

Duck hunt! That would be so alsome to play on vc again with the Zapper.

No, the Zapper isn't necessary; it is indeed a plastic shell. Some lightgun games may even be easier with the wiimote and nunchuck held normally... but the thing will be $20 and will come with the Zelda crossbow game, so it's probably worth it. (note that REUC and Ghost Squad are $50).