[RightWhale]

It is thought that Einstein said that nothing can exceed the speed of light. Gravity waves would therefore move no faster than c. However, I don't know that Einstein actually said that. Minkowski did say that, and much of the popular conception of special relativity is due to Minkowski. I don't see the problem, since we're talking about appearances of electromagnetic phenomena, not the reality behind them.

[ruiner]

AFAIK nothing with MASS can exceed or equal the speed of light. Massless objects can, which is why light (massless) can go lightspeed and not really really really really close to it :)

[Brellium]

Einstein said that nothing can be accelerated beyond the speed of light in a vaccum.