Did Einstein plagiarize Poincare? http://www.bibliotecapleyades.net/esp_einstein.htm
This site makes such claims including:

Jules Henri Poincaré (1854 - 1912) was a great scientist who made a significant contribution to special relativity theory. The Internet Encyclopedia of Philosophy website says that Poincaré:
  "sketched a preliminary version of the special theory of relativity"
  "stated that the velocity of light is a limit velocity" (in his 1904 paper from the Bull. of Sci. Math. 28, Poincaré indicated "a whole new mechanics, where the inertia increasing with the velocity of light would become a limit and not be exceeded")
  suggested that "mass depends on speed"
  ("formulated the principle of relativity, according to which no mechanical or electromagnetic experiment can discriminate between a state of uniform motion and a state of rest"
  "derived the Lorentz transformation"
  It is evident how deeply involved with special relativity Poincaré was.
Even Keswani (1965) was prompted to say that,
  "As far back as 1895, Poincaré, the innovator, had conjectured that it is impossible to detect absolute motion", and that "In 1900, he introduced 'the principle of relative motion' which he later called by the equivalent terms 'the law of relativity' and 'the principle of relativity' in his book, Science and Hypothesis, published in 1902".
  Einstein acknowledged none of this preceding theoretical work when he wrote his unreferenced 1905 paper. 
In addition to having sketched the preliminary version of relativity, Poincaré provided a critical part of the whole concept - namely, his treatment of local time. He also originated the idea of clock synchronization, which is critical to special relativity. 

Are these claims incorrect?
I already know Hilbert was wrong.
Edit: more info from quora: http://www.quora.com/Did-Einstein-plagiarize-Henri-Poincar%C3%A9?no_redirect=1
 A: I think you have to read "Science and hypothesis". It's a little book, easy and pleasant to read. And yes, Poincaré was SO close of special relativity. He did the mathematical work, he certainly wrote E=MC2 before Einstein (maybe some others like Hamilton did since you can find this formula with Hamilton Mechanic, but we will never know), and in his book, he was carefully and slowly going in the right direction. BUT he kept the Ether. 
And Einstein in his 1905's paper, first page wrote :
"The introduction of a “luminiferous ether” will prove to be superfluous inasmuch as the view here to be developed will not require an “absolutely stationary space” provided  special properties, nor assign a velocity-vector to a point of the empty space in which electromagnetic processes take place."
And that is why Einstein took the credit. As a French guy, I really think that Poincaré was close and definitely in the right direction. But Einstein is the father of Special Relativity because he went further when Lorentz or Poincaré didn't dare. The reason I think can be because Einstein was a total outsider, nobody knew him in 1905, he was living an anonymous life and was not afraid of anything, when Poincaré was a famous guy, with more to lose and also older than Einstein. I guess when you get older, it's harder to break foundation of your knowledge.
