While the NRA and other pro-Second Amendment groups are gearing up for a supposed assault from the left, I think nothing will come of it. If anything, the Virginia Tech shooting will help gun rights advocates. Here's my logic:
When a shooting takes place where guns are permitted or where the victims are children (who could not have legally owned guns), it sets up a what-if situation and allows the anti-gun crowd to say, "See? If only society had banned handguns this could've been prevented."
However, if a shooting takes place where guns are already banned and where, unlike in Columbine, the victims could've legally had guns to defend themselves had they not been, the anti-gun lobby receives a one-two punch.
First, the shooting is a real-life example proving the futility of trying to keep guns away from criminals by banning them: Guns were banned, but a criminal violated the law and brought a gun where he wasn't supposed to. People are left thinking, "Gun laws don't stop criminals."
Secondly, the defenselessness of the victims highlights how devastating not having a gun is when you need one. People are left thinking, "If only the students had guns too!"