What Real Experiments Explore the Speed of Gravity?

[Alvydas]

Can you advice a good list of real experiments related to speed of gravity?

And here is simple thought experiment:

version 1 with Shapiro delay
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(source of gravitational and light wave)..>......(star)
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version 2 without Shapiro delay

As I understand wavefront of light would look like in version 1.
But which type of wavefront would have gravitational wave?

 

[Chronos]

Kopeikin and Formalont [http://arxiv.org/abs/astro-ph/03110632003] is one example. It is, however, controversial.