The landscape has certainly changed, and as stated before, the radar gun (I believe) has contributed as much if not more than anything else, although how anyone can prove that is another story.
The obvious overuse -- pitching in games too close together without proper rest, playing on multiple teams, and going to showcases without the proper conditioning, and training will certainly increase the likelihood of injury. Apart from that, I still believe we are seeing injuries. Whether they are because of the medical technology that is available to diagnose, and therefore we hear more reported injuries than before, or because they are truly higher is anyone's guess.
What I do know is fact: velocity is king, and every pitcher is trying to blow up the radar gun. Every showcase, scouted tournament, even some HS have the radar readings on the scoreboards. Heck its not even fun to watch a game on TV without the MPH next to the box score. I was with Jr. last weekend watching a Big 12 game, and the MPH reading on the scoreboard was not turned on....it didn't take but a few pitches, and Jr. asked, "dad - what do you think he is throwing?"