I think one of the worst parts of all this is that he was actually dating the girl who plays his girlfriend on the show (Lea Michelle), and the show creators are going to have to address it all somehow. That couldn't be a more gut-wrenching scene to be contractaully obligated to depict, you mourning the loss of your fictional boyfriend while you're actually morning his death in real life.
Hopefully the show creators will deal with it with some tact. I never know how shows can move forward with this sort of thing... I remember when I was younger my family used to watch the Highlander TV show, and at one point the main character's mentor's actor died. In the show they did some clever editing and wove his death into the story and made it a huge plot point, but it's a lot harder to do something like that in a show like Glee.
I don't really trust the Glee show makers to handle this well if they incorporate it into the show. At all.
The show's creator, Ryan Murphy, was talking about how his death might bring in tons of viewers for next season... so sleazy.