In a recent issue of UXM, there was a scene where Northstar attacks the X-Men. There's the dialogue box that states something like:
"Speed of light 186,000....."
"Speed of servos in Cyclops' visor - considerably slower".
Now, i guess there are two options to think of here. The writer COULD be talking abour Northstar and his ability to potentially reach the speed of light (at the last time i read up on this guy, he theoretically could, but his bodily limitations were such that he couldn't: someone update me if this is wrong now). Equally though, it's perfectly possible that the "speed of light" reference was about the speed of Scott's blasts.
I've always thought the blasts are the speed of light....