I have read, that as a rocket approaches light speed, objects in front of it become blue shifted and also intensity of light increases. Does this mean that at some point any rocket will be destroyed, just because the blue-shift will cause impacting photons to become gamma rays of arbitrary high energy - so high in fact that no material could withstand it?
The intensity will not increase (of course you have to be careful in the definition of intensity because it's trivial that intensity depends on the speed of shuttle since it's, in its simplest form, defined as the rate of flow of photons per unit time), but the frequency will change, and all the photons from the Cosmic Microwave Background (CMB) will become gamma rays, which could more kill the people in the shuttle more likely than affecting the ship itself.
However, the rocket will be destroyed not because of the photons, but more likely because of the atoms scattered in the universe, which will turn into projectiles hitting the rocket with the speed of light. I think that's a bigger problem that photons which can be shielded by lead.
Urlich Walter has published many articles about this, and gave a seminar I attended in PSI (Paul Scherrer Institute in Switzerland). Take a look at his publications.